Managing GLP-1 Side Effects: A Practical Guide

The big picture

Most side effects of GLP-1 medications like semaglutide (Wegovy, Ozempic) and tirzepatide (Zepbound, Mounjaro) affect the stomach and gut. They are usually mild to moderate, and they fade with time.

Here is what to expect:

• They start early. Side effects usually begin within 2 days of starting the medication or raising the dose (1-3).
• The first 2 months are the hardest. Symptoms tend to peak in the first 8 weeks, then ease once your dose stays steady (1-3).
• Bigger doses mean more side effects. That is why doses are raised slowly (1-3).
• Most people stay on treatment. In clinical trials, only 6 to 10 out of 100 people stopped because of side effects (2).

Two main tools to feel better: adjusting how fast your dose goes up, and changing what and how you eat (3-4).

How common is each side effect?

Nausea is by far the most common side effect, followed by constipation. The table shows how many people out of 100 had each symptom on the highest dose of each drug, compared with people taking a placebo (a dummy shot) (3).

Symptom	Semaglutide 2.4 mg	Placebo	Tirzepatide 15 mg	Placebo
Nausea	44%	16%	28%	8%
Constipation	24%	11%	11%	5%
Tiredness	11%	5%	7%	3%
Indigestion	9%	3%	10%	4%
Burping	7%	under 1%	5%	1%
Bloating	7%	5%	4%	2%
Acid reflux (heartburn)	5%	3%	5%	2%

Notice that some people on placebo also had these symptoms. Only the difference between the two columns is caused by the medication.

Nausea

Nausea usually improves by going slower with your dose and eating smaller, simpler meals.

Go slow with your dose. Treatment starts at the lowest dose (0.25 mg for semaglutide, 2.5 mg for tirzepatide). If you feel sick, ask your doctor about staying on your current dose for another 2 to 4 weeks before going up, or stepping back down to your last dose. In trials, people could stay on one dose for up to 8 weeks. Some doctors simply keep patients on the lowest dose that is working (2-4).

Change how you eat. Eat small, planned meals. Eat slowly and stop as soon as you feel full. Avoid fatty foods, spicy foods, alcohol, and fizzy drinks (2, 4).

Don't go long without eating. Nausea is often worse in the morning or after long stretches without food. Skipping meals makes nausea worse, which makes you want to eat even less. Break the cycle with a small breakfast, then small meals every 3 to 4 hours (3).

Try simple home remedies. Ginger or peppermint tea, acupressure wristbands, and avoiding strong smells can help. Some people find that crackers or a mint about 30 minutes after their shot settles the stomach (3, 5).

Ask about anti-nausea medicine. For bad days, your doctor may prescribe an anti-nausea medicine for short-term use. Ondansetron (Zofran) is common but can make constipation worse, so prochlorperazine may be a better choice for some people (2-3).

Consider a different drug. If nausea doesn't settle, another GLP-1 medication such as dulaglutide (Trulicity) may be easier to tolerate, although it usually leads to less weight loss (4).

Constipation

The best approach to constipation is to prevent it from day one with fluids and fiber.

Prevent it early. Drink plenty of fluids, even if you don't feel thirsty. These medications reduce thirst, which makes it easy to get dehydrated. Add fiber slowly over a few weeks. Prunes and other dried fruit are especially helpful (2-3).

Step up if needed. If prevention isn't enough, these over-the-counter options can help (2-3):

• Psyllium (Metamucil), a fiber supplement
• Polyethylene glycol (MiraLAX), a gentle laxative
• Magnesium citrate, adjusted until you have regular bowel movements
• Docusate (Colace), a stool softener that reduces straining

Adjust heavy meals. Meals high in protein or fat slow your stomach down even more. You may need to cut back on them for a while. Long-lasting constipation can sometimes cause watery stool to leak around a blockage, which can look like diarrhea (3).

Be careful with Zofran. If you are already constipated, avoid ondansetron (Zofran) for nausea, as it can make constipation worse (3).

Knowledge is only half the battle

Knowing what to do is not the same as getting it done

Most side effects can be managed, but what works depends on your dose schedule, what you eat, and when you eat it. Finding the pattern behind your symptoms is much easier with someone who has seen it many times.

This guide gives you the best evidence available, but research describes averages, and you are not an average. As a physician, I have worked with hundreds of people on GLP-1s. I combine the highest quality evidence with that experience and with your specific situation, preferences, and goals to build a plan that works for you, then adjust it as you go.

Book a free 30-minute callHow coaching works

Tiredness

Tiredness is real but less common: about 11 in 100 people on semaglutide, compared with 5 in 100 on placebo (3). We don't fully understand why it happens, but these are the most likely causes to check:

• Not eating enough. Many people eat far fewer calories and much less protein than before (3, 6).
• Dehydration. Vomiting, diarrhea, or simply drinking less can dry you out. Severe dehydration can also strain the kidneys (3).
• Low blood sugar. This is a risk mainly if you also take insulin or a sulfonylurea such as glipizide (1, 3).
• Muscle loss. Losing weight quickly can mean losing muscle too. Eating enough protein (about 1.0 to 1.5 grams per kilogram of body weight per day, or roughly 0.45 to 0.7 grams per pound) and doing strength training can help protect it (6-7).

Bloating, heartburn, and sulfur burps

These symptoms happen because food stays in your stomach longer than usual. Semaglutide is the GLP-1 most strongly linked to heartburn and burping (3, 8).

Heartburn and reflux. Keep meals small and avoid alcohol. Wait at least 2 to 3 hours after eating before lying down. If it continues, ask about an acid reducer such as famotidine (Pepcid) or omeprazole (Prilosec) (2-4).

Bloating and gas. Eat slowly and skip fizzy drinks. Cut back on foods that cause gas, such as broccoli, cabbage, beans, sugar-free sweets made with sugar alcohols, and other high-FODMAP foods (2, 7, 9).

Sulfur burps ("rotten egg" burps). There is no research specifically on these. They are treated the same way as other burping and indigestion: small low-fat meals, eating slowly, and an acid reducer if needed (2-3).

What to eat on bad days

On days when you feel sick, eat a little bland food often instead of skipping meals.

• Eat small amounts every 3 to 4 hours. Choose plain, light foods rather than going all day without eating (3, 7, 9). Intermittent fasting has become very popular but it may not be the best fit for someone taking a GLP-1.
• Pick foods that are easy on the stomach. Low-fat foods with lots of water, such as melon, berries, cucumber, and broth-based soups, leave the stomach faster (3).
• Keep drinking. Sip water and sugar-free drinks throughout the day. If you are vomiting, add an electrolyte drink (4, 9).
• Skip the heavy stuff. Avoid fried or fatty food, alcohol, and hard exercise right after eating. A light walk should be fine (4).

What's normal and when to call your doctor

Mild stomach symptoms after a dose increase are expected. Severe pain, ongoing vomiting, or signs of dehydration are not.

Normal. Mild to moderate nausea, constipation or diarrhea, feeling full quickly, burping, and mild tiredness, especially after a dose increase. These usually improve within about 4 weeks on a steady dose (3, 10).

Call your doctor promptly if you have:

• Severe or constant belly pain, which can be a sign of pancreatitis (an inflamed pancreas) (10)
• Pain in the upper right belly, fever, or yellow skin or eyes, which can be signs of gallbladder problems. These drugs raise that risk by about 1.5 times (1, 10)
• Vomiting that won't stop, trouble keeping fluids down, dizziness, or very little urine, which are signs of dehydration that can harm the kidneys (3)
• Ongoing nausea, vomiting, bloating, feeling full after a few bites, or weight loss you can't explain, which may mean the stomach has slowed down too much (gastroparesis). Your doctor will likely stop the medication (11)
• Shakiness, sweating, or confusion if you also take insulin or a sulfonylurea, which may be low blood sugar (3)
• Changes in your vision, especially if you have diabetic eye disease (3, 10)
• Signs of an allergic reaction, mood changes, or thoughts of self-harm. No clear link to suicidal thoughts has been proven, but you should still report them (3)

Before any surgery or procedure, tell your care team you take a GLP-1 medication. Food can stay in your stomach longer, which raises the risk of breathing it into your lungs during anesthesia (1).

This guide is for education only and is not medical advice. Talk with your prescriber before changing or stopping your medication.

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More in the GLP-1 guide series

• How to Eat on a GLP-1
• Protecting Your Muscle on a GLP-1
• Is My GLP-1 Working?
• Why Isn't the Scale Moving?
• Keeping the Weight Off

References

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2. Kushner RF, Almandoz JP, Rubino DM. Managing adverse effects of incretin-based medications for obesity. JAMA. 2025.
3. Mozaffarian D, Agarwal M, Aggarwal M, et al. Nutritional priorities to support GLP-1 therapy for obesity: a joint advisory from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association, and the Obesity Society. Am J Clin Nutr. 2025.
4. Ndumele CE, Rodriguez F, Dixon DL, et al. 2026 AHA/ACC/ADA/ASN guideline for the prevention, detection, evaluation, and management of cardiovascular-kidney-metabolic syndrome. J Am Coll Cardiol. 2026.
5. Bellavance D, Chua S, Mashimo H. Gastrointestinal motility effects of GLP-1 receptor agonists. Curr Gastroenterol Rep. 2025.
6. Ueda P. GLP-1 receptor agonists and serious adverse events: evidence, uncertainty and clinical implications. J Intern Med. 2026.
7. Rockwell MS, Polk EA, Mittendorf C. Coprescribing GLP-1 receptor agonists and lifestyle. JAMA Intern Med. 2026.
8. Ismaiel A, Scarlata GGM, Boitos I, et al. Gastrointestinal adverse events associated with GLP-1 RA in non-diabetic patients with overweight or obesity: a systematic review and network meta-analysis. Int J Obes. 2025.
9. de Paulo RS, Bonifácio DB, de Carvalho MHL, Bressan J. Dietary strategies and nutritional management in patients receiving GLP-1 and dual GIP/GLP-1 receptor agonists as adjuncts to lifestyle interventions: a systematic review of randomised clinical trials. Diabetes Obes Metab. 2026.
10. Honigberg MC, Chang LS, McGuire DK, et al. Use of glucagon-like peptide-1 receptor agonists in patients with type 2 diabetes and cardiovascular disease: a review. JAMA Cardiol. 2020.
11. Olubodun T, Osundina MA, Soyoye DO, et al. Gastroparesis induced by glucagon-like peptide-1 receptor agonists: a systematic review of clinical features, diagnosis, management, and outcomes. PLoS One. 2026.