Wegovy® (semaglutide) is FDA-approved for chronic weight management in adults with obesity, or with overweight and at least one weight-related medical condition, used alongside a reduced-calorie diet and increased physical activity. Like other GLP-1 receptor medications, it comes with a well-documented side effect profile, most of it gastrointestinal, along with a smaller set of less common but more serious warnings. Knowing what is common, what is rare, and when a symptom is worth a call to your clinician can make starting or continuing treatment feel less uncertain.
This article is patient education, not medical advice. It does not create a doctor-patient relationship and is not a substitute for an individualized evaluation from a licensed clinician who knows your health history.
What Wegovy® is and how it is dosed
Wegovy® contains the active ingredient semaglutide, a GLP-1 receptor agonist that slows digestion, reduces appetite, and helps regulate blood sugar. The FDA approved Wegovy® for chronic weight management in adults with obesity, or with overweight and at least one weight-related condition such as high blood pressure, type 2 diabetes, or high cholesterol, when used together with a reduced-calorie diet and increased physical activity. It is given as a once-weekly injection under the skin, typically in the abdomen, thigh, or upper arm.
Semaglutide is also sold as Ozempic®, which is FDA-approved for type 2 diabetes rather than weight management, and is available as a compounded medication through licensed U.S. pharmacies. Compounded medications are not FDA-approved, while the FDA-approved brand products, Ozempic®, Wegovy®, Mounjaro®, and Zepbound™, have each been evaluated by the FDA for safety, effectiveness, and quality. Our comparison of compounded semaglutide vs. Wegovy® looks at how the two differ beyond dosing alone.
Wegovy® is started at a low dose and increased roughly every four weeks according to a fixed schedule until a maintenance dose is reached. That gradual approach is central to how side effects are managed in practice, which the dosing section below covers in more detail. Because semaglutide stays active in the body for roughly a week between doses, side effects from a dose increase can take a few days to appear and a week or more to settle, which is part of why clinicians ask patients to track symptoms across the full week rather than just the day of an injection.
Gastrointestinal effects are the most frequently reported side effects in the Wegovy® prescribing information. Nausea, diarrhea, vomiting, constipation, and abdominal pain are the ones most people notice, and most describe them as mild to moderate, though individual experience varies and some people notice very little at all. Our general overview of side effects of GLP-1 medications covers this same pattern across the drug class.
| Category | Examples | Typical timing | What to do |
|---|---|---|---|
| Most commonly reported | Nausea, diarrhea, vomiting, constipation, abdominal pain | Often most noticeable during dose increases | Mention to your clinician; often manageable without stopping treatment |
| Other common effects | Headache, fatigue, indigestion, dizziness | Can occur at any point in treatment | Report if persistent or bothersome |
| Serious warnings | Pancreatitis, gallbladder problems, acute kidney injury from dehydration, diabetic retinopathy complications | Can occur at any time | Contact your clinician promptly |
| Boxed warning | Thyroid C-cell tumors (seen in rodent studies) | Contraindication, not an acute symptom | Not recommended with personal or family history of MTC or MEN 2 |
Serious warnings on the label
Beyond the common gastrointestinal effects, the Wegovy® label carries a boxed warning, the FDA's strongest form of warning, about the risk of thyroid C-cell tumors that were seen in rodent studies. Because of this, Wegovy® is not recommended for anyone with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). It is not known whether semaglutide causes thyroid C-cell tumors in humans.
Other labeled warnings include pancreatitis (inflammation of the pancreas), gallbladder problems such as gallstones, acute kidney injury that can result from dehydration tied to gastrointestinal side effects, and complications of diabetic retinopathy in people with type 2 diabetes who have a history of that condition. Dehydration severe enough to affect the kidneys is generally tied to vomiting or diarrhea that has gone on for more than a day or two without enough fluid replacement, which is one reason clinicians ask patients to flag gastrointestinal symptoms that are not easing rather than waiting them out. Our deeper look at GLP-1 medications and gallbladder health explains why that particular warning comes up so often with this drug class.
The label also notes a risk of low blood sugar (hypoglycemia) when Wegovy® is combined with insulin or a sulfonylurea, and the possibility of a serious allergic reaction, even though these are reported less frequently than the gastrointestinal effects above.
Mood is also part of ongoing monitoring during treatment, though the picture here has shifted over time. The FDA revisited GLP-1 medications and suicidal thoughts more than once, and most recently, in January 2026, asked that suicidal-thoughts warning language be removed from the Wegovy® label after a comprehensive review found no increased risk, a change covered in our article on GLP-1 medications and mood. Even with that update, patients are still asked to tell their clinician about any new or worsening depression or unusual change in mood or behavior, since that kind of monitoring continues as standard practice regardless of the specific warning language on file.
Why gradual dose increases matter
Gastrointestinal effects are most often reported during dose escalation, the four-week stretch in which a new, higher dose is first introduced, and they tend to ease for many people as the body adjusts, though this varies from person to person. Starting low and increasing gradually is intended to improve tolerability rather than to delay results, giving the digestive system time to adjust at each step. Our guide to what to expect in the first month of GLP-1 treatment walks through what that early adjustment period typically looks like.
Because of this pattern, a clinician may respond to bothersome side effects by slowing the pace of future increases, staying at a current dose longer than originally planned, or in some cases stepping back to a lower dose, rather than automatically stopping treatment. Simple habits can also make dose increases more comfortable for many people, such as eating smaller meals, slowing down while eating, avoiding very rich or greasy food right after a dose increase, and keeping up with fluids, though these are general comfort measures rather than a substitute for your clinician's specific guidance. Side effects that appear right after an increase and then settle over the following days or weeks follow a fairly typical pattern; symptoms that are severe or are not improving are a different matter, covered in the next section.
Questions to bring to a clinician
A short list of questions can make it easier to get the most out of an appointment about Wegovy® side effects. Consider asking which side effects are expected to ease with time and which ones should prompt a call right away, whether your current pace of dose increases is appropriate given what you have noticed so far, and whether any of your other medications or health conditions, such as a personal or family history of thyroid cancer, pancreatitis, or gallbladder disease, should change how your treatment is monitored.
It is also worth raising specific symptoms directly rather than waiting to be asked: severe or persistent abdominal pain, with or without vomiting, which can be a sign of pancreatitis; pain in the upper right abdomen, fever, or yellowing of the skin or eyes, which can point to a gallbladder problem; symptoms of a serious allergic reaction, such as swelling of the face, lips, tongue, or throat, or difficulty breathing; or signs of dehydration, such as dizziness or a significant reduction in urination, especially alongside ongoing vomiting or diarrhea. Do not change your own dose, skip a scheduled check-in, or stop treatment on your own without talking to your clinician first.
The bottom line
Most people who take Wegovy® experience gastrointestinal side effects such as nausea, diarrhea, or constipation, especially around dose increases, and these are generally the most common and most manageable effects on the label. Less common but more serious warnings, including a boxed warning about thyroid C-cell tumors seen in rodent studies, pancreatitis, gallbladder problems, and kidney injury linked to dehydration, are far less frequent but are the reason to stay alert for specific warning signs. Severe or persistent symptoms are always worth a call to your clinician rather than waiting them out. You can find more articles like this one in our Weight Management section.
Important Safety Information
Indication. Wegovy® (semaglutide) is FDA-approved for chronic weight management in adults with obesity, or with overweight and at least one weight-related medical condition, used along with a reduced-calorie diet and increased physical activity. Semaglutide is also FDA-approved as Ozempic® for type 2 diabetes. Compounded semaglutide is not FDA-approved.
Common side effects. The most commonly reported side effects include nausea, diarrhea, vomiting, constipation, abdominal pain, headache, fatigue, and indigestion; these are often more noticeable in the days after a dose increase.
Warnings. Wegovy® carries a boxed warning regarding thyroid C-cell tumors seen in rodent studies and is contraindicated in people with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2. Other warnings include the risk of pancreatitis, gallbladder problems, acute kidney injury related to dehydration from gastrointestinal side effects, diabetic retinopathy complications in people with type 2 diabetes, hypoglycemia when used with insulin or sulfonylureas, and serious hypersensitivity reactions. Tell your provider about any history of depression or suicidal thoughts, and report any new or worsening mood changes.
Talk to your doctor. This information is educational and is not a substitute for medical advice. Only a licensed medical professional can determine whether a treatment is right for you. Talk to your doctor about the benefits and risks, and report any side effects.
Frequently asked questions
What are the most common Wegovy® side effects?
Gastrointestinal effects such as nausea, diarrhea, vomiting, constipation, and abdominal pain are the most commonly reported side effects in the Wegovy® prescribing information. Headache, fatigue, and indigestion are also commonly reported.
How long do Wegovy® side effects last?
Gastrointestinal effects are most often reported during dose escalation and tend to ease for many people as the body adjusts to each new dose, though this varies from person to person. Symptoms that are severe or are not improving are a different matter and are worth a call to your clinician.
What is the boxed warning for Wegovy®?
The Wegovy® label carries a boxed warning about the risk of thyroid C-cell tumors seen in rodent studies. Wegovy® is not recommended for people with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2.
Can Wegovy® cause gallbladder problems?
Yes, gallbladder problems, including gallstones, are a labeled warning for Wegovy®. Contact your clinician promptly for pain in the upper right abdomen, fever, or yellowing of the skin or eyes.
Does compounded semaglutide have the same side effects as Wegovy®?
Compounded semaglutide shares the same active ingredient, but compounded medications are not FDA-approved, while FDA-approved brand products are evaluated by the FDA for safety, effectiveness, and quality. Use the side effect profile described here as a starting point for a conversation with your clinician, since your own experience may differ.
When should I call my clinician about Wegovy® side effects?
Call promptly for severe or persistent abdominal pain, signs of a serious allergic reaction, signs of dehydration, or nausea, vomiting, or diarrhea that is severe or is affecting your ability to eat, drink, or take other medications as prescribed.
