Semaglutide side effects: what the label lists

The side effects on the Ozempic®, Wegovy® and Rybelsus® labels, why they cluster early, sulfur burps and nausea, the serious warnings, and when to call.

Semaglutide is the active ingredient in Ozempic®, Wegovy® and Rybelsus®, and in the compounded semaglutide GLP's clinicians prescribe. This article restates what the FDA-approved labels list as side effects and warnings, explains the pattern most people notice, and says when to contact a clinician. It is not a substitute for the medication guide that comes with a prescription.

What are the most common semaglutide side effects?

The Ozempic® label lists nausea, vomiting, diarrhea, abdominal pain and constipation as the most common. The Wegovy® label, which covers a higher maintenance dose, adds headache, fatigue, indigestion, dizziness, bloating, burping, gas, heartburn, stomach flu and, in people with type 2 diabetes, low blood sugar. The Rybelsus® tablet's list is led by nausea, abdominal pain, diarrhea, reduced appetite, vomiting and constipation. Almost all of it is gastrointestinal, and most is described as mild to moderate.

Why do side effects cluster early and after dose increases?

Semaglutide slows how quickly the stomach empties and acts on appetite signals; the body adjusts to each dose over weeks. Side effects are reported most in the first weeks and after each step up, which is why the labels start everyone at 0.25 mg and hold each step for four weeks. A prescriber can keep someone at a step longer, or go back one, when the current dose is not being tolerated.

What are sulfur burps, and why do they happen?

Burping is a listed side effect of semaglutide, and some people describe theirs as smelling of sulfur. The usual explanation is slower digestion: food sits longer in the stomach, and the gases produced come back up. Smaller, lower-fat meals, eating slowly, and avoiding foods you notice make it worse tend to help. Tell your care team if it is persistent or comes with pain or vomiting.

What helps with nausea?

• Smaller portions, eaten slowly, and stopping when full rather than when the plate is empty.
• Bland, low-fat food on the days after an injection; greasy or very sweet food is what people most often report sitting badly.
• Fluids across the day; vomiting and diarrhea can dehydrate, which is one of the ways kidney problems arise on the label.
• Telling your care team early. Holding a dose step is routine; suffering through one is not required.

What are the serious warnings?

All three labels carry a boxed warning about thyroid C-cell tumors seen in animal studies, and contraindicate semaglutide in anyone with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2. The warnings sections cover acute pancreatitis, acute gallbladder disease, low blood sugar when combined with insulin or sulfonylureas, serious allergic reactions, acute kidney injury linked to dehydration, complications of diabetic retinopathy, and pulmonary aspiration during general anesthesia or deep sedation, which is why patients are told to tell anyone sedating them that they take it. The Wegovy® label also advises monitoring for depression or suicidal thoughts.

Who should not take semaglutide?

Anyone with the contraindications above, anyone who has had a serious allergic reaction to it, and anyone who is pregnant, planning a pregnancy or breastfeeding. A history of pancreatitis or gallbladder disease, significant gastrointestinal conditions, type 1 diabetes, and medications that affect blood sugar all call for a clinician's judgment.

When should I contact a clinician?

Promptly, for severe or persistent abdominal pain (with or without vomiting, sometimes felt in the back), signs of gallbladder trouble such as pain in the upper right abdomen or yellowing skin, vomiting that will not stop, signs of dehydration, vision changes, a fast heartbeat, or a lump or hoarseness in the neck. For swelling of the face or throat, trouble breathing, or any medical emergency, call 911. For anything else that concerns you, message your care team; adjusting a plan is routine.

Are compounded semaglutide's side effects the same?

The active ingredient is the same, so the same warnings apply. Compounded semaglutide is prepared by a licensed compounding pharmacy for an individual patient. Compounded medications are not FDA-approved and are not reviewed by the FDA for safety, effectiveness, or quality. Report anything unexpected to your care team.

This article is educational and is not a substitute for personalized medical advice. Whether any medication is appropriate for you is a decision for a licensed clinician who has reviewed your health history.