- Stomach side effects are common: about 44% of people on Wegovy® 2.4 mg and 25 to 29% on Zepbound® reported nausea in trials.
- They are worst while the dose is rising and usually ease over the following weeks. Most people who stop because of side effects do so in the first few months.
- Eating smaller, slower, plainer meals and drinking enough are the most useful fixes. Ask about holding a dose step if it is too much.
- Get help quickly for severe stomach pain that does not go away, persistent vomiting, signs of dehydration, or yellowing skin or eyes.
- Changed in 2026: FDA removed the suicidal thoughts warning from Wegovy® and Zepbound® after reviewing 91 trials.
How common side effects are
These figures come from the clinical trials summarised in each drug's prescribing information. They are the best guide available to what is likely 12.
| Side effect | Wegovy® 2.4 mg | Zepbound® 5 / 10 / 15 mg | Placebo |
|---|---|---|---|
| Nausea | 44% | 25% / 29% / 28% | 8–16% |
| Diarrhea | 30% | 19% / 21% / 23% | 8–16% |
| Vomiting | 24% | 8% / 11% / 13% | 2–6% |
| Constipation | 24% | 17% / 14% / 11% | 5–11% |
| Stomach pain | 20% | Reported | About 10% |
| Hair loss | 3% | 5% / 4% / 5% | 1% |
| Stopped because of side effects | 6.8% | 4.8% / 6.3% / 6.7% | 3.2–3.4% |
Placebo figures differ between the two drugs' trials; the range covers both. The trials were separate, so compare the two drugs loosely.
Two things stand out. Many people on placebo also reported stomach symptoms, so not everything you feel is the medicine. And most people who get side effects carry on: fewer than 7 in 100 stopped because of them.
When they happen: a typical first few months
Side effects follow the dose. Every GLP-1 starts low and increases in steps, usually every four weeks, and symptoms tend to flare for a few days after each step and then settle 12.
- Weeks 1 to 4, starting dose. Many people notice a smaller appetite and feel full quickly. Mild nausea is common in the first days.
- Each dose increase. Expect a few days of stronger effects: nausea, a heavy stomach, constipation or loose stools.
- Months 3 to 5, approaching the usual dose. The highest doses bring the most weight loss and, for some, the most side effects. This is when people most often ask to hold a dose for longer.
- Once the dose is steady. For most people symptoms ease. Most of those who stop because of side effects do so in the first few months 2.
What helps
Clinical recommendations for managing these side effects are practical and mostly about eating differently 67:
- Eat smaller meals, more slowly, and stop as soon as you feel full. The medicine slows your stomach, so overeating is what usually brings on nausea.
- Go easy on fatty, fried and very spicy food, and on strong smells when you feel sick. Plain food and ginger can help.
- Do not lie down straight after eating.
- Drink enough, especially if you have vomiting or diarrhea. Dehydration is the route to the more serious kidney problems.
- For constipation, fluids, fibre and movement help; ask about a gentle laxative if it persists.
- For diarrhea, avoid sugar-free products sweetened with sugar alcohols.
- Protect your muscle with enough protein and some resistance exercise, as nutrition advisories for people on GLP-1s recommend 7.
- Ask about the dose. The labels allow a dose increase to be delayed, or a lower usual dose to be kept, if side effects are too much 12. You do not have to push on to the highest dose.
Two obesity medicine doctors on what to expect and how to cope:
Serious side effects: when to get help
These are uncommon, but the labels list them as warnings, and you should contact a clinician promptly, or seek urgent care, if you notice them 12:
- Severe stomach pain that does not go away, sometimes spreading to the back, with or without vomiting. This can be pancreatitis.
- Pain in the upper right of the stomach, fever, yellowing skin or eyes, or pale stools. These can be gallbladder problems, which are more likely with rapid weight loss.
- Persistent vomiting or diarrhea, or signs of dehydration such as dizziness, very dark urine or passing little urine. Dehydration can damage the kidneys.
- Signs of a serious allergic reaction: swelling of the face, lips or throat, trouble breathing, or a severe rash.
- A lump or swelling in the neck, trouble swallowing or a hoarse voice. All three drugs carry a boxed warning about thyroid C-cell tumours seen in rodents. They should not be used by anyone with a personal or family history of medullary thyroid cancer or MEN 2 123.
- Low blood sugar (shakiness, sweating, confusion) if you also take insulin or a sulfonylurea for diabetes.
What changed in 2026
In January 2026, FDA asked the makers of Wegovy®, Zepbound® and Saxenda® to remove the warning about suicidal thoughts and behaviour from their labels. Its review of 91 placebo-controlled trials covering more than 100,000 people found no increased risk 4. Older articles that tell readers to watch for this specifically are out of date. Anyone noticing a change in their mood should still speak to a clinician.
The new Wegovy® 7.2 mg dose brought one new common side effect: a tingling, burning or sensitive feeling in the skin, reported by 22% of people on that dose 1.
Hair loss, muscle loss and "Ozempic face"
- Hair loss was reported by a small share of people in the trials, more often by women: 7.1% of women on Zepbound® against 0.5% of men 2. It is linked to rapid weight loss, is usually temporary, and nobody on Zepbound® in the trials stopped because of it.
- Muscle loss. Both labels say the medicines cause more fat loss than lean-tissue loss. In one scan sub-study, about a quarter of the weight people lost on tirzepatide was lean mass 8. Protein and resistance exercise help keep it.
- "Ozempic face" describes a hollower look after weight loss. Published reviews attribute it to losing facial fat quickly and to skin that has not tightened yet, rather than to the medicine itself.
Pregnancy, contraception and surgery
- Birth control pills may work less well on Zepbound® and Foundayo®, because the stomach empties more slowly. Use a non-oral method, or add a barrier method, for four weeks (30 days for Foundayo®) after starting and after each dose increase 23.
- Planning a pregnancy: stop Wegovy® at least two months beforehand, because semaglutide stays in the body for a long time 1. Stop any GLP-1 if you become pregnant, and talk to your clinician.
- Surgery or sedation: tell the team you take a GLP-1. Rare cases of food being inhaled under anaesthesia have been reported. Current multi-society guidance is that most people can continue, with a liquid diet for 24 hours beforehand for those at higher risk 9.
Compounded medicines: an extra check
If you use a compounded semaglutide or tirzepatide, FDA has reports of side effects caused by dosing mistakes, such as confusing milligrams with syringe units, and by doses increased faster than the approved schedules 10. If side effects suddenly get much worse, check your dose and how you measured it before anything else. Our guide to dosing, units and storage explains how.
A program with ongoing clinician access makes all of this easier to manage. Our #1 pick, TotalRx, includes unlimited clinician check-ins and dose adjustments in its price.
Questions and answers
What are the most common side effects of semaglutide and tirzepatide?
Nausea, diarrhea, vomiting, constipation and stomach pain. In the Wegovy® trials, 73% of people had at least one digestive side effect, against 47% on placebo; on Zepbound® it was 56% against 30%.
How long do GLP-1 side effects last?
They are most frequent in the days after starting or increasing a dose and tend to fade over the following weeks. For Zepbound®, most nausea, vomiting and diarrhea happened during dose increases and decreased over time.
Does semaglutide or tirzepatide cause hair loss?
Hair loss was reported in a small share of people in the trials, more often in women: for example 3.3% on Wegovy® 2.4 mg against 1% on placebo, and 7.1% of women on Zepbound®. It is linked to rapid weight loss rather than to the drug directly, and it is usually temporary.
Do GLP-1s cause muscle loss?
Some of the weight lost is lean mass, which includes muscle. In a scan sub-study of SURMOUNT-1, about a quarter of the weight lost was lean mass. Eating enough protein and doing resistance exercise helps protect muscle.
What is 'Ozempic face'?
A popular term for a hollower look in the face after weight loss. Published reviews put it down to fat loss and loosening skin from rapid weight loss, not to an effect of the drug itself.
Is the suicidal thoughts warning still on Wegovy and Zepbound?
No. In January 2026 FDA asked the manufacturers to remove it after a review of 91 placebo-controlled trials found no increased risk. If you notice changes in your mood, you should still talk to a clinician.
Can I take birth control pills on tirzepatide?
Zepbound® can make birth control pills less reliable. Its label advises switching to a non-oral method or adding a barrier method for four weeks after starting and after each dose increase.
Should I stop my GLP-1 before surgery?
Tell the team doing your procedure that you take one. Current guidance says most people can continue, with a liquid diet for 24 hours beforehand for those at higher risk, but the decision is theirs.
Keep reading
Sources
- Wegovy® prescribing information (revised June 2026)
- Zepbound® prescribing information (revised August 2026)
- Foundayo® prescribing information (revised July 2026)
- Psychiatric Times: FDA removes suicidal behavior and ideation warning from GLP-1 receptor agonists (January 2026)
- American College of Cardiology: SURMOUNT-5 journal scan
- Gorgojo-Martínez et al., Clinical recommendations to manage gastrointestinal adverse events with GLP-1 receptor agonists, J Clin Med 2023
- Joint advisory (ACLM, ASN, OMA, TOS): nutritional priorities for people on GLP-1 medications, Am J Clin Nutr 2025
- SURMOUNT-1 body composition sub-study, Diabetes Obes Metab
- American Society of Anesthesiologists: multi-society guidance on GLP-1s before procedures (2024)
- FDA: concerns with unapproved GLP-1 drugs used for weight loss
How we write our guides. We read the manufacturers' prescribing information, FDA and other official sources, published trials and each provider's own pricing and policies, and link to them so you can check our work. Figures were correct when we last checked them on October 19, 2026; prices and rules change often, so confirm them before you act. Medical disclaimer. This guide is general information, not medical advice, and no one at ProviderCompare is your clinician. Talk to a licensed healthcare professional before starting, changing or stopping any medication. Compounded GLP-1 medications are not FDA-approved and do not undergo FDA review for safety, effectiveness or quality. Brand names are trademarks of their owners, used for identification only.