Wegovy Side Effects
Wegovy (semaglutide) is a once weekly injection approved for weight management. This page explains the side effects named in its FDA approved prescribing information, in plain language: the reactions reported most often, when they tend to happen, and the serious warnings on the label. It is education only, not medical advice.
The most common Wegovy side effects
Most of the reactions reported with Wegovy involve the stomach and digestion, because the medicine slows stomach emptying and reduces appetite. The reactions named as most common in the prescribing information are:
- Nausea. The most frequently reported reaction, especially in the first weeks and after increases.
- Diarrhea. Loose or frequent stools, common while the dose is going up.
- Vomiting. Often connected to dose increases or to eating past the point of fullness.
- Constipation. Slower digestion can mean less frequent, harder stools.
- Stomach pain. Abdominal pain or discomfort, listed on the label as abdominal pain.
- Headache and fatigue. Both listed among the common reactions, alongside dizziness.
- Indigestion, belching and reflux. Dyspepsia, eructation, flatulence and gastroesophageal reflux all appear on the label.
Hair loss also appears in the reactions reported in the Wegovy trials. Shedding during weight loss treatment is usually tied to the rapid weight loss itself, and our GLP-1 hair loss guide explains why that happens. Not everyone gets these effects, and the pattern varies a lot from person to person.
When side effects tend to happen
The stomach related reactions are reported most often during dose escalation, when the dose is stepped up every four weeks. The Wegovy dosage chart shows that climb, from 0.25 mg up to the 2.4 mg maintenance dose. The early low doses are there to let the body adjust. For many people, reactions that flare after an increase ease once the dose stays the same for a while. Side effects that are severe or not settling are a common reason a prescriber holds a dose for longer instead of stepping up on schedule.
Warnings in the Wegovy prescribing information
Boxed warning: thyroid C-cell tumors. The strongest warning on the label is about a possible risk of thyroid C-cell tumors. In animal studies, semaglutide caused these tumors in rodents. It is not known whether Wegovy causes them in people. The label says the medicine should not be used by people with a personal or family history of medullary thyroid carcinoma, or with a condition called multiple endocrine neoplasia syndrome type 2.
Pancreatitis. Inflammation of the pancreas has been reported with this class of medicine. The label describes severe stomach pain, sometimes spreading to the back, as the warning sign.
Gallbladder problems. Gallstones and gallbladder inflammation have been reported, and rapid weight loss itself raises gallstone risk. Pain in the upper right stomach area, fever, or yellowing of the skin or eyes are the signs the label points to.
Severe stomach problems. Because Wegovy slows stomach emptying, the label states it is not recommended for people with severe gastroparesis, a condition where the stomach already empties too slowly.
Diabetic retinopathy complications. The label carries a warning for people who have diabetic retinopathy, a diabetes related eye condition, and advises that vision changes be reported.
Allergic reactions. Serious allergic reactions, including anaphylaxis and swelling of the face, lips or tongue, have been reported with semaglutide medicines.
When to get medical care promptly
Some symptoms should never be waited out. Seek medical care promptly for severe or persistent stomach pain, signs of an allergic reaction such as swelling of the face, lips or tongue or trouble breathing, yellowing of the skin or eyes, or a lump or swelling in the neck, a hoarse voice, or trouble swallowing. Ongoing vomiting or diarrhea that stops you drinking enough fluid also deserves a prompt call, because dehydration can strain the kidneys.
Frequently asked questions
What are the most common side effects of Wegovy?
The Wegovy prescribing information lists nausea, diarrhea, vomiting, constipation and stomach pain among the most common reactions, along with headache, fatigue, indigestion, dizziness, belching, gas and reflux. Most of the list involves the stomach and digestion, which fits how the medicine works.
Do Wegovy side effects settle down over time?
For many people, yes. The stomach related reactions are reported most often during dose escalation, while the dose is stepped up every four weeks. As the body adjusts to a steady dose, they often become milder or less frequent, although not for everyone, and severe or ongoing symptoms should always be raised with the prescriber.
Is hair loss a Wegovy side effect?
Hair loss appears in the list of reactions reported in the Wegovy trials. Shedding during treatment is usually linked to the rapid weight loss itself rather than a direct effect of the medicine on hair, and it is typically temporary. Our GLP-1 hair loss guide explains the mechanism in more detail.
What is the boxed warning on the Wegovy label?
The boxed warning is about thyroid C-cell tumors. In studies, semaglutide caused these tumors in rodents. It is not known whether Wegovy causes them in people. Because of this, the label says the medicine should not be used by people with a personal or family history of medullary thyroid carcinoma, or with multiple endocrine neoplasia syndrome type 2.
When should someone taking Wegovy get medical care promptly?
The warnings on the label point to a few situations: severe or persistent stomach pain, which can be a sign of pancreatitis; signs of a serious allergic reaction such as swelling of the face, lips or tongue or trouble breathing; yellowing of the skin or eyes; and a lump or swelling in the neck, hoarseness or trouble swallowing.