Table of Contents
Introduction
Semaglutide is a medicine that helps people manage blood sugar levels and body weight. It is part of a group of drugs called GLP-1 receptor agonists. These medicines work by copying a hormone in the body called GLP-1, which helps control how much insulin is made after eating. Semaglutide is used to treat type 2 diabetes and to help with weight loss in people who are overweight or have obesity. It can be taken by injection once a week or as a daily pill, depending on the form prescribed.
At the same time, influenza—or the flu—is a common and sometimes serious viral infection that spreads easily from person to person. It affects the nose, throat, and lungs. Flu symptoms can include fever, chills, sore throat, cough, and muscle aches. For most people, the flu goes away after a few days of rest, but for others, especially older adults, children, and those with health problems like diabetes, it can lead to more serious illness or even death.
Every year, doctors and scientists watch how the flu spreads and changes. Flu viruses often mutate, which means that the virus looks slightly different from one year to the next. This is why flu vaccines need to be updated each year. The flu shot helps protect people by training the immune system to fight off the virus. Even though the flu is common, it still causes millions of illnesses, hundreds of thousands of hospital stays, and tens of thousands of deaths every year across the world.
People who take semaglutide usually have diabetes or are overweight. These health conditions can also make it harder to fight off infections like the flu. That’s why there is growing interest in understanding if medicines like semaglutide change how the body responds to viruses. Some people are asking whether semaglutide could make the flu worse, or if it could change how the body reacts to the flu virus or to the flu vaccine. Others wonder whether taking semaglutide could increase the chances of getting sick in the first place.
There are many questions about how flu and semaglutide may be linked, and some of those questions have started to appear online. People are turning to search engines to ask things like: “Can semaglutide make the flu worse?”, “Is it safe to take semaglutide while sick?”, or “Does semaglutide weaken the immune system?” These questions show that many patients and caregivers are trying to find answers about safety and how to best manage both chronic and temporary illnesses.
Medical researchers are beginning to look more closely at how the body’s immune system works in people taking GLP-1 receptor agonists like semaglutide. Early studies have shown that these medicines may do more than just help with blood sugar and weight—they might also affect inflammation and other immune responses in the body. These effects could change how a person deals with infections like the flu, though much more research is needed to understand this better.
This article looks at what is currently known about the connection between semaglutide and influenza. It brings together the most common questions that people ask about the two and tries to answer them based on current science and medical guidance. By explaining how semaglutide works, what the flu does to the body, and what studies show about possible risks or safety concerns, this article will help provide clearer information. The goal is to help patients, families, and healthcare professionals make informed choices, especially during flu season or when facing sickness while on semaglutide treatment.
What Is Semaglutide and How Does It Work?
Semaglutide is a type of medicine used to treat two main conditions: type 2 diabetes and obesity. It helps lower blood sugar levels and can also support weight loss. Semaglutide belongs to a group of drugs called GLP-1 receptor agonists. GLP-1 stands for glucagon-like peptide-1, which is a natural hormone made in the body, mostly in the gut.
After eating, the body releases GLP-1 to help control blood sugar levels. It does this in three main ways:
- It helps the pancreas release the right amount of insulin.
- It lowers the amount of sugar made by the liver.
- It slows down how fast food leaves the stomach, which helps people feel full longer.
Semaglutide copies the action of natural GLP-1. It binds to GLP-1 receptors in the body and triggers the same helpful actions, but it lasts longer than the body’s natural hormone. This makes it more effective for managing blood sugar and weight over time.
Forms and Dosing of Semaglutide
Semaglutide comes in three main brand-name forms:
- Ozempic: This is an injection taken once a week. It is used mainly for managing type 2 diabetes.
- Wegovy: Also a once-weekly injection, Wegovy is used for long-term weight management.
- Rybelsus: This is the only version that comes in a pill. It is taken by mouth once a day and is used for type 2 diabetes.
The injectable forms are usually started at a low dose and then slowly increased over a few weeks. This helps lower the chance of side effects, especially nausea or stomach discomfort.
How Semaglutide Helps With Diabetes
In type 2 diabetes, the body either does not make enough insulin or does not use it well. This leads to high blood sugar levels. Semaglutide helps lower blood sugar by increasing insulin only when it is needed. It also blocks the release of another hormone called glucagon, which raises blood sugar. Together, these effects make semaglutide helpful in keeping blood sugar stable.
Semaglutide can also help protect the heart. Studies have shown that people with type 2 diabetes who use semaglutide have a lower risk of heart attacks and strokes. This makes it a strong option for people with both diabetes and heart disease risk.
How Semaglutide Helps With Weight Loss
Semaglutide is also used to help people lose weight, especially those who are overweight or have obesity. It works by slowing down digestion, which helps people feel full sooner and for longer. It also acts on brain areas that control hunger and fullness. Many people taking semaglutide eat less and lose weight steadily over several months.
This weight loss effect is not just helpful for appearance. Losing weight can also lower the risk of heart disease, high blood pressure, sleep apnea, and even some types of cancer.
How Long Semaglutide Stays in the Body
One reason semaglutide is given weekly is because it stays in the body for a long time. It has a long half-life, which means it breaks down slowly. Most people only need to take the injection once every seven days to keep a steady level of the drug in the body. The pill form, Rybelsus, works a little differently and needs to be taken daily for best results.
Safety and Common Side Effects
Most people who use semaglutide do well, but like all medicines, it can cause side effects. The most common ones are nausea, vomiting, diarrhea, and constipation. These side effects usually get better over time as the body adjusts to the drug.
More serious side effects are rare but can happen. These may include pancreatitis, kidney problems, or allergic reactions. Because semaglutide slows digestion, it can also affect how the body handles other medicines or illnesses, especially those that involve vomiting or dehydration.
Semaglutide is not the same as insulin and does not replace insulin for people who need it. It is not used for treating type 1 diabetes or diabetic ketoacidosis.
What Is Influenza?
Influenza, often called the flu, is a common illness caused by a virus. It spreads easily from person to person, especially during the colder months of the year. Many people get the flu each year, and while most recover in a week or two, it can sometimes lead to serious health problems.
Types of Influenza Viruses
There are three main types of influenza viruses that affect humans: Influenza A, Influenza B, and Influenza C.
- Influenza A is the most common type. It can cause large outbreaks and even pandemics. This virus can infect both humans and animals. Influenza A viruses change often, which makes them harder to predict and control.
- Influenza B usually causes smaller outbreaks and is only found in humans. It can still cause severe illness but tends to spread more slowly than Influenza A.
- Influenza C is less common and usually causes mild symptoms. It does not lead to major outbreaks or serious disease.
Influenza viruses change over time through a process called mutation. This means new forms of the virus appear each year, which is why flu vaccines are updated regularly to match the most likely strains for that season.
How Influenza Spreads
The flu spreads mainly through droplets in the air when a person coughs, sneezes, or talks. These droplets can land in the mouths or noses of people nearby. The virus can also be picked up from surfaces like doorknobs, phones, or hands. A person can get sick after touching a surface with the virus and then touching their eyes, nose, or mouth.
People with the flu are most contagious in the first 3 to 4 days after symptoms begin, but they can start spreading the virus even before they feel sick. Some people, especially young children and those with weak immune systems, can stay contagious for longer.
Symptoms of Influenza
The flu usually starts suddenly. A person might feel fine in the morning and very sick by the evening. Common symptoms include:
- Fever or chills
- Cough
- Sore throat
- Runny or stuffy nose
- Muscle or body aches
- Headache
- Fatigue (feeling tired)
- Sometimes vomiting and diarrhea, more common in children
Not everyone with the flu will have a fever. Some people may just feel very tired and have a cough.
Flu Season and Yearly Changes
In many parts of the world, flu season happens during the fall and winter. In the United States, it usually starts in October and can last until May, with most cases happening between December and February.
Every year, scientists study the flu viruses that are spreading and use this information to create the flu vaccine for the next season. Since the virus changes often, people are encouraged to get a new flu shot every year to stay protected.
Complications and Who Is at Risk
Most people with the flu get better within a week or two. But for some, the illness can lead to serious health problems. These are called complications and can include:
- Pneumonia (an infection in the lungs)
- Bronchitis
- Sinus and ear infections
- Worsening of existing health conditions like asthma or heart disease
- Hospitalization or, in rare cases, death
Some people are at higher risk of complications. These include:
- Adults 65 and older
- Children under 5, especially under 2 years old
- Pregnant women
- People with chronic illnesses like diabetes, asthma, or heart disease
- People with weakened immune systems
Preventing the Flu
The best way to prevent the flu is by getting a flu vaccine each year. The vaccine helps the body build protection against the most common types of flu viruses expected for that season. Other ways to reduce the risk of flu include washing hands often, covering coughs and sneezes, avoiding close contact with sick people, and staying home when feeling unwell.
Flu is a serious and widespread illness, but with the right steps, many of its effects can be prevented or lessened. Vaccines, good hygiene, and early care are important tools in staying healthy during flu season.
Can Semaglutide Affect the Immune System?
Semaglutide is a medicine used to help manage blood sugar and support weight loss. It works by copying a natural hormone in the body called GLP-1, or glucagon-like peptide-1. This hormone helps control blood sugar, slows digestion, and reduces hunger. While semaglutide is mainly used for diabetes and obesity, researchers are now asking whether it may also have effects on the immune system.
The Link Between Metabolism and Immunity
The body’s metabolism and immune system are closely connected. When someone has type 2 diabetes or obesity, the immune system often becomes weaker or acts in unusual ways. This can lead to more inflammation and a higher risk of infections, such as the flu. Medicines that improve metabolism, like semaglutide, may also change how the immune system works.
Some early research shows that GLP-1 receptor agonists (the class of drugs that includes semaglutide) might help reduce inflammation. Inflammation is the body’s natural response to injury or infection, but too much of it can damage tissues and organs. By lowering inflammation, these medicines may help protect the body, especially in people with long-term conditions like diabetes.
How Semaglutide Might Influence Immune Cells
GLP-1 receptors are not just found in the pancreas and stomach. They are also found in other areas of the body, including the lungs, heart, and even immune cells. Studies in animals and some lab tests show that activating these receptors may change how immune cells respond to infections. For example, GLP-1 activity might help lower the activity of certain white blood cells that cause inflammation.
In people with diabetes, GLP-1 medicines like semaglutide have been shown to reduce levels of markers linked to inflammation, such as C-reactive protein (CRP) and interleukin-6 (IL-6). These are substances the body makes when it is fighting off infection or stress. Lower levels of these markers can mean less overall stress on the immune system.
Research on Infections and GLP-1 Agonists
Some studies have looked at how often people get sick while using semaglutide and similar drugs. The results are mixed. A few large clinical trials showed a small increase in reports of upper respiratory infections, such as the common cold, in people taking GLP-1 agonists. However, the increase was very small and may not be directly caused by the medicine. It could also be due to other health problems or lifestyle factors.
Most importantly, no strong evidence shows that semaglutide weakens the immune system or makes people more likely to catch serious infections like influenza. The U.S. Food and Drug Administration (FDA) and other health agencies have not issued any warnings linking semaglutide to changes in immune function.
Possible Benefits for Immune Health
Improving blood sugar control may help support the immune system. High blood sugar can damage blood vessels and slow down the response of immune cells. By helping people reach healthier glucose levels, semaglutide may allow their immune systems to work more effectively. This could lower the risk of complications if they get sick.
There is also growing interest in how semaglutide might reduce chronic, low-level inflammation in people who are overweight or obese. This kind of inflammation is different from the kind caused by infections. It can last for years and put stress on the immune system. Lowering this type of inflammation could help the body fight off new infections more easily.
Limitations in Current Knowledge
Although there are signs that semaglutide might affect the immune system in positive ways, the science is still new. Most studies so far have focused on animals or lab samples. More research in people is needed to understand exactly how semaglutide and other GLP-1 drugs affect immunity.
Doctors do not currently prescribe semaglutide to boost the immune system or to treat any immune-related diseases. Its main use is still for managing type 2 diabetes and supporting weight loss. Any possible immune-related benefits are still being studied.
Semaglutide may affect the immune system by reducing inflammation and improving metabolic health. These effects could help the body respond better to infections, but more research is needed. For now, semaglutide remains a safe and effective medicine for its approved uses, without any proven harmful effects on immune health.
Does Semaglutide Increase the Risk of Getting Influenza?
Many people who take semaglutide for type 2 diabetes or weight loss worry about how it might affect their immune system. One common question is whether semaglutide makes someone more likely to catch the flu. The flu, also known as influenza, is a virus that spreads easily and can cause mild to serious illness. Since semaglutide changes how the body works, including how it handles sugar and hormones, some have wondered if it could also change the way the body fights infections.
What Clinical Trials Say
So far, there is no strong proof that semaglutide increases the chance of getting the flu. Clinical trials for semaglutide included thousands of people and lasted several months to years. In these studies, researchers looked for all types of side effects, including infections like colds and the flu. Some people in the trials did report getting sick with upper respiratory infections, which includes symptoms like a runny nose, sore throat, and cough. These are common symptoms of the flu but can also be caused by other viruses.
However, the number of people who got these infections was similar in both the semaglutide group and the placebo group (the group that took a fake treatment). This means the chance of getting the flu or similar illnesses did not appear to be higher for people taking semaglutide.
For example, in one large trial called the SUSTAIN-6 study, researchers followed patients with type 2 diabetes. They found no meaningful difference in the number of flu-like illnesses between those taking semaglutide and those who were not. These results suggest that semaglutide does not weaken the immune system in a way that increases flu risk.
Real-World Reports and Side Effects
Outside of clinical trials, doctors and scientists continue to monitor people who take semaglutide. This is called real-world evidence or post-marketing surveillance. In these settings, doctors may report any health problems their patients experience while using a drug. So far, these reports do not show an increase in flu infections linked to semaglutide.
Some patients do report feeling tired or having stomach upset, such as nausea or vomiting, when they first start semaglutide. These side effects are known and are caused by how semaglutide slows digestion and affects appetite. Feeling tired or unwell can make it harder to notice flu symptoms, especially early on. But this does not mean the medicine causes the flu. It is more likely that flu symptoms may be confused with side effects.
Understanding the Difference Between Correlation and Causation
It is important to understand the difference between correlation and causation. Just because someone taking semaglutide catches the flu does not mean the medicine caused it. People still get common infections while on many different types of medications. These events can happen at the same time without being connected. A proper study would need to compare groups of people to see if those on semaglutide really do get the flu more often, and so far, studies have not shown this.
What Health Experts Say
Health agencies such as the U.S. Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) have not issued warnings about semaglutide increasing flu risk. The official drug labels for semaglutide products like Ozempic, Wegovy, and Rybelsus do not list the flu as a known or likely side effect. If the flu were a common or serious risk with this medicine, the FDA would be required to update the label and share that information with doctors and patients.
Some people taking semaglutide also have other health conditions, like diabetes or obesity, which already make them more likely to get very sick from the flu. These conditions, not semaglutide, are the known risk factors. That is why health experts strongly recommend annual flu shots for people with these medical problems.
Current evidence does not show that semaglutide increases the risk of catching the flu. While mild infections like colds may happen during treatment, they occur at similar rates in people who are not taking the drug. Clinical trials, real-world data, and health guidelines all suggest that semaglutide is not linked to a higher chance of getting influenza. People taking semaglutide should continue to follow normal flu prevention steps, such as handwashing and getting vaccinated, just like everyone else.
What Happens if You Get the Flu While Taking Semaglutide?
Getting the flu can make it harder for the body to stay in balance, especially for people taking medications like semaglutide. Semaglutide is often used to manage blood sugar in people with type 2 diabetes or to support weight loss in those with obesity. It helps by making the body produce more insulin, slowing down how fast the stomach empties, and reducing hunger. However, when a person becomes sick with the flu, many body functions change. These changes can affect how semaglutide works and how safe it is to keep using it during illness.
The Flu Can Lead to Problems With Food and Fluids
One of the main effects of the flu is a loss of appetite. People often eat much less while they are sick. Semaglutide also reduces appetite. This can become a problem when both the flu and semaglutide are working at the same time to lower hunger. Some people might eat too little, leading to weakness, dizziness, or low blood sugar—especially if they are also taking insulin or other blood sugar-lowering drugs.
Flu can also cause vomiting or diarrhea, which leads to fluid loss. This can make a person dehydrated. Semaglutide may increase the risk of dehydration because it can cause nausea and vomiting as side effects. When these symptoms happen together, dehydration may become severe. Dehydration can affect kidney function and can be dangerous, especially in older adults or people with kidney problems.
Because semaglutide slows down how quickly the stomach empties, vomiting caused by the flu can feel worse. Food may stay in the stomach longer, making nausea stronger. People who already have trouble with nausea while on semaglutide may feel even more uncomfortable if they catch the flu.
Should Semaglutide Be Continued During the Flu?
Doctors often recommend that people continue taking their medications during short illnesses. However, with semaglutide, the decision may depend on how sick the person is. If the person is still able to eat and drink enough fluids, it may be safe to keep using semaglutide. But if the person is vomiting a lot, has diarrhea, or cannot keep food or fluids down, stopping semaglutide for a short time may be the safer choice.
There is no need to stop the medication forever. Usually, semaglutide can be restarted once the flu has passed and eating and drinking return to normal. It is important that people who stop semaglutide during illness talk to a doctor before restarting it. Depending on how many doses were missed, a lower starting dose may be needed to avoid side effects when beginning again.
If semaglutide is taken once a week, the timing of the next dose should be considered carefully. If vomiting or severe nausea is present, it may be wise to delay the dose by a few days. Taking the medication while the stomach is upset may worsen symptoms.
Watch for Signs of Low Blood Sugar or Dehydration
For people with diabetes, having the flu while taking semaglutide raises the risk of low blood sugar. This is especially true if food intake is very low or missed entirely. Blood sugar should be checked more often during illness. Warning signs of low blood sugar include shakiness, sweating, headache, confusion, and feeling very tired.
At the same time, signs of dehydration should also be watched for. These include dark urine, dry mouth, fast heartbeat, and dizziness when standing. Anyone showing these signs should drink more fluids and may need to see a doctor, especially if unable to keep fluids down.
Medical Advice Is Important During Illness
A doctor, nurse, or pharmacist should be contacted if symptoms from the flu are severe while taking semaglutide. They can help decide whether to stop or continue the medication and may give other advice, such as how to stay hydrated and when to return to a normal dosing schedule. People with diabetes may also be told to adjust other medications during flu illness to keep blood sugar levels stable.
Semaglutide is a powerful medicine that works well under normal conditions, but flu infection puts extra stress on the body. When used carefully and with guidance during illness, semaglutide can still be part of a safe and effective treatment plan.
Does Semaglutide Interact with Influenza Vaccines or Antivirals?
Semaglutide is a medication used to treat type 2 diabetes and help with weight loss. It works by acting on a hormone called GLP-1 (glucagon-like peptide-1), which helps control blood sugar, appetite, and digestion. Since many people take semaglutide long term, it’s important to understand if it can safely be used alongside other common treatments—like the flu shot or antiviral medications used to treat influenza.
Safety of Flu Vaccines with Semaglutide
The flu vaccine is the best protection against seasonal influenza. It helps the body build immunity by teaching the immune system how to recognize and fight the virus. Every year, millions of people receive a flu shot, including those with diabetes or obesity—two groups that are also often prescribed semaglutide.
There is no medical evidence that semaglutide interferes with how flu vaccines work. Because semaglutide does not weaken the immune system, it should not reduce the body’s ability to respond to a vaccine. Clinical studies and real-world use have not shown any harmful interactions between semaglutide and flu vaccines.
In fact, people with chronic conditions like diabetes are strongly advised to get a flu shot each year. The Centers for Disease Control and Prevention (CDC) recommends annual influenza vaccination for nearly everyone over the age of six months. This includes people taking medications like semaglutide. Receiving the vaccine can lower the risk of severe illness, hospitalization, or complications that could arise from the flu.
Timing of Flu Shots While on Semaglutide
Semaglutide can be taken before or after a flu shot without changing its dose or schedule. The two do not interfere with each other. For those using injectable semaglutide, such as Ozempic or Wegovy, the vaccine can be given in the opposite arm or leg to avoid irritation. There is no need to stop or skip semaglutide around the time of vaccination unless there are other health issues that require it.
Some people may experience mild flu-like symptoms after getting vaccinated, such as a low fever or body aches. These are common side effects and are not caused by semaglutide. They are signs that the body is building protection against the virus.
Use of Antiviral Drugs with Semaglutide
When someone catches the flu, doctors may prescribe antiviral medicines such as oseltamivir (Tamiflu), zanamivir (Relenza), or baloxavir (Xofluza). These medications help shorten the length of the illness and reduce the chance of serious complications. They work best when taken within 48 hours of the first symptoms.
There is no known interaction between semaglutide and any of the commonly used antiviral medications for influenza. Patients can safely take both treatments at the same time if needed. Since semaglutide and flu antivirals work in different ways and act on different systems in the body, they do not interfere with one another.
Pharmacists and doctors routinely review drug interactions before prescribing new medications. So far, semaglutide has not shown any harmful combinations with flu treatments. However, people who are very ill, vomiting, or unable to eat may need to pause semaglutide for a short time to avoid complications like dehydration. This is more about managing side effects than about drug interactions.
Semaglutide does not interfere with flu vaccines or antiviral medications. It is safe to get a flu shot while taking semaglutide, and there is no need to change the schedule or dose of either treatment. People who get the flu while on semaglutide can take antiviral medicine without concern about interactions. Doctors recommend keeping up with vaccinations and seeking antiviral treatment quickly if flu symptoms develop, especially for those at higher risk of complications. Taking semaglutide does not prevent someone from getting the protection or benefits of flu treatments.
Can Semaglutide Help or Hinder Flu Recovery?
Semaglutide is a medicine that helps manage blood sugar and supports weight loss. It works by copying a hormone called GLP-1, which helps control appetite, slow down digestion, and improve how the body uses insulin. Some researchers believe this medicine might also affect inflammation in the body. Inflammation is part of the immune system’s way of fighting infections like the flu.
When someone gets the flu, the body goes through a lot of stress. The immune system becomes very active to fight off the virus. This can lead to fever, body aches, and tiredness. In some cases, the flu can also cause problems like pneumonia or make other health conditions worse. For people taking semaglutide, it’s important to understand whether the medicine will help or hurt the recovery process.
Semaglutide and Inflammation
Some studies suggest that semaglutide and other GLP-1 medicines can reduce inflammation in the body. Lower inflammation might be helpful during the flu, especially in people who are at higher risk of severe illness, such as those with obesity or type 2 diabetes. Inflammation plays a role in how the body reacts to infections, but too much inflammation can be harmful. By lowering this response slightly, semaglutide may help the body recover more smoothly.
For example, semaglutide has been linked to lower levels of a marker called C-reactive protein (CRP), which goes up during inflammation. Some scientists think that lowering CRP might protect against damage caused by the immune system during illness. However, it is still not clear if this effect helps people recover from the flu faster or with fewer complications. More research is needed to know for sure.
Challenges During Flu Recovery
While semaglutide may offer some benefits through its effect on inflammation, there are also concerns during flu recovery. One of the most common side effects of semaglutide is nausea. It can also cause vomiting and diarrhea, especially in the early stages of treatment or after a dose increase. These side effects may become worse during a flu infection.
The flu often causes symptoms like stomach upset, fatigue, and poor appetite. If someone is already feeling sick and is also experiencing nausea from semaglutide, it may become difficult to eat or drink enough. Dehydration is a serious risk in this situation. Without enough fluids, the body cannot function well. In severe cases, this can lead to problems like kidney injury or low blood pressure.
Another concern is blood sugar levels. For people with diabetes, not eating enough while taking semaglutide can lead to low blood sugar. This is called hypoglycemia. It can cause shakiness, confusion, and even fainting. People with diabetes often need to check their blood sugar more often when they are sick. If the levels drop too low, they may need to adjust their medicine.
What Doctors Recommend
Doctors often tell patients to follow “sick day rules” when they are ill. These rules include drinking plenty of fluids, eating small meals, and monitoring blood sugar more often. If nausea or vomiting makes it hard to keep food down, doctors might recommend stopping semaglutide until the person feels better. This helps lower the risk of dehydration and other complications.
Stopping the medicine for a short time is usually safe, but it is important to start it again properly after recovery. Because semaglutide is long-acting, the medicine stays in the body for a while, so missing a dose or two may not cause a big problem. Still, a doctor should be the one to decide when to stop or restart treatment.
Semaglutide may have both helpful and harmful effects during flu recovery. It might reduce inflammation, which can be good. But it also causes side effects that may make flu symptoms worse. People who are sick should watch for signs of dehydration or low blood sugar. Medical advice is important to stay safe during recovery. Taking care with diet, fluids, and rest helps the body heal, whether or not semaglutide is continued during illness.
How Flu-Related Symptoms Impact Semaglutide Efficacy or Safety
Influenza, also known as the flu, can cause a variety of symptoms that may affect how semaglutide works in the body. These symptoms include fever, fatigue, body aches, sore throat, cough, nausea, vomiting, and diarrhea. When these symptoms occur, especially those that affect the stomach or digestion, they can change how the body responds to medications like semaglutide.
Loss of Appetite and Reduced Food Intake
One of the most common symptoms of the flu is a loss of appetite. People often eat much less than usual when they are sick. This becomes important for those who take semaglutide, especially individuals with type 2 diabetes. Semaglutide helps lower blood sugar by increasing insulin release and slowing down the movement of food in the stomach. If food intake is suddenly reduced, blood sugar levels can drop too low, causing a condition called hypoglycemia.
Hypoglycemia can cause symptoms like dizziness, shaking, sweating, confusion, and even fainting. Although semaglutide alone usually does not cause severe hypoglycemia, the risk increases when a person is sick and eating less. The risk is even higher if the person is also taking insulin or other blood sugar-lowering drugs.
To avoid hypoglycemia, it may be necessary to monitor blood sugar levels more often during illness. Some patients may need to eat small amounts of food more regularly, even if they do not feel hungry. Healthcare providers may adjust the dose of semaglutide or other medications temporarily until the person recovers.
Nausea and Vomiting
Nausea and vomiting are common side effects of both semaglutide and the flu. When these two causes happen at the same time, symptoms may become worse. Repeated vomiting can lead to dehydration, where the body loses too much water and electrolytes. Dehydration makes it harder for the kidneys to remove the drug from the body, which may increase the drug’s effects or side effects.
If vomiting occurs soon after taking semaglutide, it may not be clear if the medication was absorbed properly. In such cases, taking another dose may seem like a solution, but doing so could be risky. Taking too much semaglutide can cause severe nausea, low blood sugar, or other problems. It is best to wait for guidance from a doctor or nurse before deciding to take another dose after vomiting.
When vomiting is frequent or lasts more than a day, medical advice is needed. The person may need to stop semaglutide temporarily to allow the body to recover. Drinking clear fluids in small amounts and using oral rehydration solutions may help until solid foods can be eaten again.
Diarrhea and Dehydration
Diarrhea is another symptom that may occur with both the flu and semaglutide. This can also lead to dehydration, especially in older adults or people who already have kidney problems. Dehydration can cause weakness, low blood pressure, dizziness, and trouble thinking clearly.
When diarrhea is present, the body may not absorb semaglutide or other medications as well. This may reduce the drug’s effectiveness. On the other hand, slower drug removal due to dehydration could lead to increased side effects. Careful fluid intake is very important during this time. Doctors may suggest holding off on semaglutide until the person is rehydrated and feeling better.
When Dose Adjustments Are Needed
During a flu infection, semaglutide may need to be paused or adjusted, especially if symptoms like vomiting, diarrhea, or severe fatigue are present. The decision depends on how the illness is affecting the person’s ability to eat, stay hydrated, and take medications as prescribed. In some cases, a lower dose may be safer. In other cases, skipping a dose or waiting until the illness improves may be recommended.
Patients who are unable to keep food or fluids down for more than 24 hours, or who notice signs of dehydration, should contact their healthcare provider. Warning signs include dry mouth, dark urine, fast heartbeat, dizziness, or confusion. These may suggest that semaglutide should be stopped for a short period to allow the body to rest and recover.
Flu symptoms such as reduced appetite, nausea, vomiting, and diarrhea can change how semaglutide works in the body. These symptoms can increase the risk of low blood sugar and dehydration, both of which can be dangerous. To stay safe, patients may need to check blood sugar more often, drink fluids regularly, and speak with their healthcare provider about adjusting medication during illness. Proper care during the flu can help prevent serious problems and support a smooth recovery.
Is There Any Evidence Linking GLP-1 Agonists with Higher Infection Rates in General?
GLP-1 receptor agonists, such as semaglutide, are medicines used to help manage blood sugar and support weight loss. They work by copying a hormone in the body called GLP-1, which helps lower blood sugar, slow digestion, and reduce appetite. Although semaglutide is mostly used for diabetes and obesity, some people wonder if these medications might increase the chance of getting infections, especially things like the flu or other illnesses.
To answer this question, researchers have looked at studies of semaglutide and similar medicines in the same drug family. These include liraglutide, dulaglutide, exenatide, and others. All of these work in a similar way. Many large clinical trials have tested these drugs in thousands of people to see how safe they are and what side effects they may cause.
Reports from Clinical Trials
In these trials, researchers track all possible side effects, including infections. For semaglutide, some participants reported mild infections such as colds, sore throats, and urinary tract infections. However, these were not more common than in people taking a placebo or other diabetes medicines. Most of these infections were not serious and did not lead to hospitalization.
When looking across studies of all GLP-1 drugs, there is no strong proof that these medicines cause more infections. In fact, infection rates were very similar between people taking GLP-1 drugs and those taking other treatments. Some studies even showed slightly fewer infections in people using GLP-1 drugs, although the difference was not large enough to be called significant.
Focus on Respiratory Infections
Upper respiratory tract infections, such as sinus infections and the common cold, were among the most reported issues. These types of infections are very common in the general population, especially during cold and flu season. That makes it hard to tell if the medicine causes the infection or if the person would have gotten sick anyway.
So far, there is no evidence that GLP-1 drugs like semaglutide directly weaken the immune system. These medicines are not like steroids or chemotherapy drugs, which can reduce the body’s ability to fight off illness. Because of this, doctors do not consider semaglutide or related drugs to be immunosuppressive.
What About Gastrointestinal Side Effects?
GLP-1 drugs often cause side effects like nausea, vomiting, and diarrhea, especially when someone first starts the medicine or the dose is increased. These problems can make the body lose fluids and feel weak. In rare cases, this might make it harder to recover from an infection. But again, this does not mean the drug causes infections—it only means people who are already sick might feel worse if they are also having stomach problems.
Because of this, healthcare providers recommend extra care during times of illness. Patients are often told to drink plenty of fluids and watch for signs of dehydration. If vomiting or diarrhea lasts more than a day, it may be safer to skip a dose of the medicine and call a doctor.
Limits of Current Research
Even though the data from studies is helpful, it is not perfect. Most trials only last for a year or two. Long-term effects, especially rare ones, might not show up until the medicine is used by many people over time. Also, many trials do not collect detailed information about colds, flu, or other minor infections unless they are severe.
Real-world data can help fill in the gaps. This includes reports from patients and doctors outside of clinical trials. So far, these reports also do not show a clear link between semaglutide and a higher risk of infections.
Studies of semaglutide and other GLP-1 medicines have not shown a strong connection to more infections. Mild infections like colds and sore throats do happen, but they are common in everyone and do not seem to happen more often with these drugs. These medicines do not weaken the immune system, and there is no sign that they raise the risk of getting the flu or similar illnesses. While stomach side effects may affect how the body handles illness, the medicine itself does not cause more infections.
What Do Clinical Guidelines Say About Managing Semaglutide During Infections?
When someone taking semaglutide becomes sick with an infection like influenza, it is important to follow medical guidelines to stay safe and avoid problems. Infections can affect how the body handles medications, especially in people with diabetes or other long-term conditions. Trusted health organizations such as the American Diabetes Association (ADA) and the American Association of Clinical Endocrinology (AACE) provide clear advice on how to manage medications like semaglutide during illness. This is sometimes called following “sick day rules.”
Sick Day Rules for People on Semaglutide
Sick day rules are steps to follow when someone becomes ill. These steps help prevent dehydration, high or low blood sugar, and other side effects that could lead to serious health problems.
One of the first rules is to keep drinking fluids. Influenza can cause fever, chills, and sweating, which may lead to fluid loss. Vomiting and diarrhea are also common flu symptoms that increase the risk of dehydration. Dehydration can cause serious problems for people using semaglutide because the medication slows down how the stomach empties. If the stomach is not emptying well and a person is dehydrated, it can increase the risk of nausea, vomiting, or even kidney problems.
It is also important to keep eating small amounts of food if possible. If a person cannot eat normally but can still drink fluids, they should choose liquids that contain some sugar, like diluted juice or sports drinks, especially if they are at risk for low blood sugar. People with diabetes need to avoid drinking only water for long periods because it may not provide the calories needed to keep blood sugar at a safe level.
Monitoring Blood Sugar and Ketones
For people with type 2 diabetes who use semaglutide, keeping a close eye on blood sugar levels is a must during illness. Flu and other infections often cause the body to release stress hormones like cortisol, which can raise blood sugar levels. At the same time, if a person cannot eat well or is vomiting, there may also be a risk for low blood sugar, especially if using other medications such as insulin or sulfonylureas along with semaglutide.
Some people with diabetes may also need to check for ketones during illness. Ketones are acids that build up in the blood when the body burns fat for energy instead of sugar. High levels of ketones can lead to a dangerous condition called diabetic ketoacidosis (DKA). While DKA is more common in people with type 1 diabetes, it can happen in type 2 diabetes as well, especially during illness or when dehydrated.
If ketones are present or blood sugar stays very high (above 250 mg/dL for several hours), medical attention should be sought immediately. Delaying care can lead to serious complications.
Adjusting or Pausing Semaglutide
Doctors may recommend stopping semaglutide for a short time if the person becomes too sick to eat or drink normally. This is because semaglutide may cause more stomach upset in people who are already vomiting or unable to keep fluids down. It may also be paused if there is a risk of acute kidney injury, especially if the person is also taking blood pressure medications such as ACE inhibitors or diuretics, which increase the risk of dehydration.
Restarting semaglutide should only happen once normal eating and drinking resume, and the person is feeling better. Sometimes, a doctor may need to lower the dose when restarting to help the body adjust again. Patients should never change their dose or stop semaglutide without checking with a healthcare provider.
Advice for Healthcare Teams
Healthcare professionals are encouraged to give clear instructions to patients about what to do when sick. This may include preparing a “sick day plan” ahead of time. The plan should list which medications to keep taking, which ones to stop, how often to check blood sugar, when to check ketones, and when to call a doctor or visit the hospital.
Patients should be told to contact their doctor if:
- They cannot eat or drink for more than 24 hours
- They are vomiting or have diarrhea for more than a few hours
- Blood sugar remains very high or very low despite treatment
- They experience signs of dehydration like dry mouth, dizziness, or dark urine
Clear education helps prevent emergencies and keeps people with chronic conditions safe while recovering from infections like the flu.
During an illness like influenza, people taking semaglutide should follow sick day rules. These rules help manage hydration, blood sugar levels, and medication safety. Checking with a healthcare provider before stopping or restarting semaglutide is essential. Monitoring symptoms and knowing when to seek help can prevent serious health problems and support a smooth recovery.
Conclusion
Semaglutide is a medication used by people with type 2 diabetes and those trying to manage their weight. It helps lower blood sugar and also reduces appetite, which supports weight loss. It works by copying a natural hormone in the body called GLP-1, which helps with insulin release and slows digestion. At the same time, influenza, often called the flu, is a common and serious viral illness that spreads easily and affects the lungs, throat, and nose. Every year, millions of people get sick with the flu, and some can develop complications like pneumonia or dehydration, especially if they already have other health problems. Because semaglutide affects how the body processes food and controls blood sugar, many people have wondered if taking it can make someone more likely to get the flu or have a harder time recovering from it.
So far, there is no strong evidence that semaglutide increases the chance of getting the flu. Studies that tested semaglutide in large groups of people looked for side effects, including infections. The data did not show a clear link between semaglutide and a higher rate of flu infections. Some patients reported having colds or flu-like symptoms, but these were about the same in people who took semaglutide and those who took a placebo or another diabetes medicine. It is important to remember that having the flu is very common, especially in winter, so it can happen to anyone, no matter what medicine they are taking.
Semaglutide does have some effects on the immune system. GLP-1, the hormone that semaglutide copies, is known to reduce inflammation in the body. In some studies, this has shown positive effects, such as less swelling and lower markers of inflammation in people with diabetes or obesity. Because of this, some scientists believe semaglutide might even help the body respond better to certain illnesses. However, this is still being studied. More research is needed before doctors can say clearly how semaglutide affects the immune system during infections like the flu.
When someone taking semaglutide does get the flu, there are a few things to keep in mind. The flu can cause fever, vomiting, diarrhea, and loss of appetite. These symptoms can make it harder for the body to handle medications. Since semaglutide slows digestion and already affects the stomach, the flu can make side effects worse. For example, vomiting or diarrhea can cause dehydration. This is more dangerous for people taking semaglutide because dehydration can raise the risk of kidney problems or blood sugar swings. Some doctors may tell patients to pause their semaglutide if they are too sick to eat or keep fluids down.
Semaglutide does not stop the flu vaccine from working. People taking semaglutide can and should still get their flu shots. The vaccine helps the immune system fight the virus and reduces the chance of getting very sick. There are also no known problems when semaglutide is taken at the same time as antiviral flu medications, like oseltamivir (Tamiflu). These drugs work in different ways and do not interfere with each other.
One concern during the flu is that symptoms like nausea and tiredness might cause someone to eat less or miss meals. This can be risky for people with diabetes who are also using other medicines that lower blood sugar. If someone is not eating well, semaglutide can still lower blood sugar, which increases the risk of hypoglycemia, especially if it is combined with insulin or sulfonylureas. For this reason, people who are sick should check their blood sugar often, stay hydrated, and talk to their doctor if symptoms become worse or last too long.
Guidelines from diabetes organizations recommend special care during illness. These are called “sick day rules.” They include steps like drinking plenty of fluids, checking blood sugar and ketones regularly, and knowing when to stop taking certain medications. These rules help prevent dangerous problems such as diabetic ketoacidosis or severe dehydration. People on semaglutide are encouraged to follow these rules closely and call a healthcare provider if unsure about what to do.
There is still a lot to learn about how semaglutide interacts with the immune system, especially during viral illnesses. As more people use this medication for diabetes and weight loss, doctors and researchers are watching closely for any new patterns in side effects or complications. For now, the best approach is to stay informed, take steps to prevent flu by getting vaccinated, and talk to a doctor when flu symptoms appear.
In summary, semaglutide is not known to increase the risk of getting the flu, and it does not stop the flu vaccine from working. Still, flu symptoms can affect how the body responds to semaglutide. Being sick may change how the medicine works and how safe it is to use. The key is careful management, good hydration, and regular medical guidance to stay safe and recover quickly.
Research Citations
Fiore, A. E., Uyeki, T. M., Broder, K., Iskander, J. K., & Cox, N. J.; Centers for Disease Control and Prevention (CDC). (2010). Prevention and control of influenza with vaccines: Recommendations of the Advisory Committee on Immunization Practices (ACIP), 2010. MMWR Recommendations and Reports, 59(RR-8), 1–62.
Jefferson, T., Di Pietrantonj, C., Rivetti, A., Bawazeer, G. A., Al-Ansary, L. A., & Ferroni, E. (2014). Vaccines for preventing influenza in healthy adults. Cochrane Database of Systematic Reviews, (3), CD001269.
Osterholm, M. T., Kelley, N. S., Sommer, A., & Belongia, E. A. (2012). Efficacy and effectiveness of influenza vaccines: A systematic review and meta-analysis. The Lancet Infectious Diseases, 12(1), 36–44.
Darvishian, M., Bijlsma, M. J., Hak, E., & van den Heuvel, E. R. (2014). Effectiveness of seasonal influenza vaccine in community-dwelling elderly people: A meta-analysis of test-negative design case-control studies. The Lancet Infectious Diseases, 14(12), 1228–1239.
Belongia, E. A., Simpson, M. D., King, J. P., Sundaram, M. E., Kelley, N. S., Osterholm, M. T., & McLean, H. Q. (2016). Variable influenza vaccine effectiveness by subtype: A systematic review and meta-analysis of test-negative design studies. The Lancet Infectious Diseases, 16(8), 942–951.
Marso, S. P., Bain, S. C., Consoli, A., Eliaschewitz, F. G., Jódar, E., Leiter, L. A., … Vilsbøll, T.; SUSTAIN-6 Investigators. (2016). Semaglutide and cardiovascular outcomes in patients with type 2 diabetes. The New England Journal of Medicine, 375(19), 1834–1844.
Wilding, J. P. H., Batterham, R. L., Calanna, S., Davies, M., Van Gaal, L. F., Lingvay, I., … Wadden, T. A. (2021). Once-weekly semaglutide in adults with overweight or obesity. The New England Journal of Medicine, 384(11), 989–1002.
Davies, M., Færch, L., Jeppesen, O. K., Pakseresht, A., Pedersen, S. D., Perreault, L., … STEP 2 Study Group. (2021). Semaglutide 2.4 mg once a week in adults with overweight or obesity, and type 2 diabetes (STEP 2): A randomised, double-blind, double-dummy, placebo-controlled, phase 3 trial. The Lancet, 397(10278), 971–984.
Sørlí, C., Harashima, S. I., Tsoukas, G. M., Unger, J., Karsbøl, J. D., Hansen, T., & Bain, S. C. (2017). Efficacy and safety of once-weekly semaglutide monotherapy versus placebo in patients with type 2 diabetes (SUSTAIN 1): A double-blind, randomised, placebo-controlled, parallel-group, multinational, multicentre phase 3a trial. The Lancet Diabetes & Endocrinology, 5(4), 251–260.
Husain, M., Birkenfeld, A. L., Donsmark, M., Dungan, K., Eliaschewitz, F. G., Franco, D. R., … PIONEER 6 Investigators. (2019). Oral semaglutide and cardiovascular outcomes in patients with type 2 diabetes. The New England Journal of Medicine, 381(9), 841–851.
Questions and Answers: Influenza and Semaglutide
A contagious respiratory illness caused by influenza viruses that infect the nose, throat, and sometimes the lungs.
Primarily through respiratory droplets when an infected person coughs, sneezes, or talks.
Fever, chills, muscle aches, cough, congestion, runny nose, headaches, and fatigue.
Annual flu vaccination, good hand hygiene, and avoiding close contact with sick individuals.
Young children, elderly adults, pregnant women, and individuals with chronic health conditions like asthma or diabetes.
A medication used to treat type 2 diabetes and obesity; it mimics the GLP-1 hormone to regulate blood sugar and appetite.
It is given either as a once-weekly subcutaneous injection or as a daily oral tablet, depending on the formulation.
Ozempic (for type 2 diabetes), Wegovy (for obesity), and Rybelsus (oral form for diabetes).
Nausea, vomiting, diarrhea, constipation, and abdominal pain.
People with a personal or family history of medullary thyroid carcinoma or those with multiple endocrine neoplasia syndrome type 2.
