Semaglutide, the active ingredient in Ozempic® and Wegovy®, is one of the most studied weight-management medicines available. Like any prescription drug, it has side effects, some common and mostly manageable, a few rare but serious. And for some people it is simply not appropriate. This article sets those out plainly, so you can have an informed conversation with your provider.
At Bellava MedAesthetics in Bedford Hills, every patient in our physician-supervised semaglutide program has a medical review before starting and regular check-ins after.
What are the most common side effects of semaglutide?
The most common side effects are digestive: nausea, diarrhea, constipation and vomiting. Others include stomach pain, bloating, indigestion, burping, heartburn, headache and tiredness.
These effects are most noticeable when you first start and each time the dose is increased. For many people they ease as the body adjusts. That is the main reason semaglutide is started at a low dose and stepped up gradually, rather than started at the full dose.
How can I reduce nausea and stomach upset?
Eat smaller meals, stop when you feel full, and avoid very fatty, fried or greasy foods.
Other practical steps people find helpful:
- Eat slowly, and don’t lie down right after eating.
- Sip water through the day; dehydration makes nausea and constipation worse.
- Choose bland foods on days you feel unsettled.
- Add fiber and fluids gradually if constipation is a problem.
- Tell your provider if symptoms are severe or not settling. Your dose schedule can be adjusted.
Persistent vomiting or diarrhea is not just unpleasant; it can lead to dehydration, which can affect the kidneys. Contact your provider rather than pushing through it.
What are the serious side effects to watch for?
Serious side effects are uncommon, but they are listed in the prescribing information and you should know the warning signs.
- Pancreatitis. Severe, persistent pain in the upper abdomen that may spread to the back, with or without vomiting. Stop the medicine and seek care.
- Gallbladder problems, including gallstones. Rapid weight loss itself raises this risk. Signs include pain in the upper right abdomen, fever, yellowing of the skin or eyes, or clay-colored stools.
- Low blood sugar, mainly in people who also take insulin or a sulfonylurea for diabetes.
- Kidney problems, usually linked to dehydration from vomiting or diarrhea.
- Serious allergic reactions, such as swelling of the face, lips, tongue or throat, trouble breathing, or a severe rash.
- Increased heart rate.
- Changes in vision in people with type 2 diabetes, related to diabetic eye disease.
- Mood changes. The Wegovy® label advises monitoring for depression or suicidal thoughts, and reporting any new or worsening changes.
Any of these warrants a call to your provider, and severe symptoms warrant urgent medical care.
What is the semaglutide boxed warning about thyroid cancer?
Semaglutide carries an FDA boxed warning about thyroid C-cell tumors. In studies in rodents, semaglutide caused these tumors. It is not known whether it causes them in people, including medullary thyroid carcinoma (MTC).
Because of that warning, the medicine is not to be used by anyone with a personal or family history of MTC or with multiple endocrine neoplasia syndrome type 2 (MEN2). Tell your provider about any lump or swelling in the neck, trouble swallowing, hoarseness or shortness of breath.
Who should not take semaglutide?
Semaglutide is not appropriate for people with a personal or family history of medullary thyroid carcinoma or MEN2, people with a known serious allergy to semaglutide, and people who are pregnant or breastfeeding.
Our semaglutide service page lists the same exclusions. In addition, extra caution and a careful conversation with your provider are needed if you have:
- A history of pancreatitis
- Gallbladder disease
- Kidney disease
- Diabetic retinopathy
- A history of depression or suicidal thoughts
- An eating disorder
- Type 1 diabetes (semaglutide is not a substitute for insulin)
Can I take semaglutide if I’m trying to get pregnant?
No. Weight loss offers no benefit during pregnancy, and the Wegovy® label advises stopping semaglutide at least two months before a planned pregnancy, because the medicine stays in the body for weeks after the last dose.
If you become pregnant while taking semaglutide, contact your provider promptly.
Does semaglutide interact with other medicines or surgery?
Yes, in a few important ways.
- Semaglutide slows stomach emptying, which can change how some oral medicines are absorbed. Give your provider a full list of everything you take.
- Combined with insulin or sulfonylureas, it raises the risk of low blood sugar, and those doses may need adjusting.
- Before any procedure with anesthesia or sedation, tell the team you take semaglutide. Slower stomach emptying matters for anesthesia safety, and your surgical team will tell you whether and when to pause it.
If you are thinking about body contouring after weight loss, our article on semaglutide and body contouring covers the timing.
Why does medical supervision matter?
Because most side effects are managed by dose timing and early attention, and the exclusions above require an honest health review before you start.
At Bellava, our program begins with a consultation and health baseline (vitals, labs if needed and body composition), uses custom, stepwise dosing, and includes regular check-ins to fine-tune your plan and manage side effects. That structure is what turns a prescription into a program.
Frequently asked questions
Do semaglutide side effects go away?
For many people, digestive side effects are strongest after starting or increasing a dose and improve over the following weeks. If they don’t, your provider may slow the dose increase.
Does semaglutide cause hair loss?
Hair shedding has been reported with weight-loss doses of semaglutide, and rapid weight loss of any kind can trigger temporary hair shedding. Mention it to your provider if you notice it.
Is “Ozempic face” a side effect?
It describes the thinner, sometimes older-looking face that can follow quick fat loss. It is a result of losing weight rather than a direct effect of the drug.
Can I drink alcohol on semaglutide?
Alcohol can worsen nausea and, for people on diabetes medicines, affect blood sugar. Ask your provider what is sensible for you.
What should I do if I miss a dose?
Follow the instructions given by your prescriber and the medication guide for your product. Don’t double up to catch up.
Start with a medical review
The best way to know whether semaglutide is safe for you is a proper health review with a medical team who will follow you through treatment. Read about Bellava’s semaglutide program, compare semaglutide, Ozempic® and Wegovy®, and book a consultation at our Bedford Hills office.
This article is general information, not medical advice, and it is not a complete list of side effects. Read the medication guide that comes with your prescription, and call your provider or seek urgent care for any severe symptom. Ozempic® and Wegovy® are registered trademarks of Novo Nordisk A/S.