The most common side effects of tirzepatide, sold as Zepbound and Mounjaro, are nausea, diarrhea, vomiting and constipation. In the Zepbound weight-loss trials, 56% of people at each dose had a gut side effect, compared with 30% on placebo, and nausea affected 25% to 29% vs 8%. The label says most nausea, vomiting and diarrhea happened while the dose was being raised in 2.5 mg steps and decreased over time. Serious problems such as pancreatitis and gallbladder disease are uncommon but need prompt care.
Key takeaways
- Zepbound starts at 2.5 mg once a week for 4 weeks, then 5 mg; the dose can rise in 2.5 mg steps after at least 4 weeks on each dose, up to 15 mg.
- In the pooled Zepbound trials, nausea was reported by 25% to 29%, diarrhea by 19% to 23% and constipation by 11% to 17%, vs 8%, 8% and 5% on placebo.
- 1.9% to 4.3% stopped Zepbound because of gut side effects, vs 0.5% on placebo; most who stopped did so in the first few months.
- Hair loss was reported by 7.1% of women and 0.5% of men on Zepbound. The label links it to weight loss.
- Severe, ongoing belly pain, sometimes spreading to your back, can be pancreatitis. Get medical care right away.
- Mounjaro is the same medicine, approved in the US for type 2 diabetes. In Mexico and much of Latin America, tirzepatide is sold as Mounjaro.
How common are Zepbound side effects?
Nausea is the most common Zepbound side effect, followed by diarrhea, constipation and vomiting. The table comes from the Zepbound label's pool of two placebo-controlled trials, SURMOUNT-1 (adults without diabetes) and SURMOUNT-2 (adults with type 2 diabetes): 2,519 adults treated for up to 72 weeks.
| Side effect | Placebo | Zepbound 5 mg | Zepbound 10 mg | Zepbound 15 mg |
|---|---|---|---|---|
| Nausea | 8% | 25% | 29% | 28% |
| Diarrhea | 8% | 19% | 21% | 23% |
| Vomiting | 2% | 8% | 11% | 13% |
| Constipation | 5% | 17% | 14% | 11% |
| Belly pain | 5% | 9% | 9% | 10% |
| Indigestion (dyspepsia) | 4% | 9% | 9% | 10% |
| Injection-site reactions | 2% | 6% | 8% | 8% |
| Tiredness (fatigue) | 3% | 5% | 6% | 7% |
| Allergic-type (hypersensitivity) reactions | 3% | 5% | 5% | 5% |
| Burping (eructation) | 1% | 4% | 5% | 5% |
| Hair loss | 1% | 5% | 4% | 5% |
| Reflux (GERD) | 2% | 4% | 4% | 5% |
| Gas (flatulence) | 2% | 3% | 3% | 4% |
| Bloating (abdominal distension) | 2% | 3% | 3% | 4% |
| Dizziness | 2% | 4% | 5% | 4% |
| Low blood pressure | 0% | 1% | 1% | 2% |
Vomiting and diarrhea rose a little with dose, while constipation was most common at 5 mg. Overall, 4.8% to 6.7% stopped Zepbound because of any side effect, vs 3.4% on placebo.
How do side effects relate to the 2.5 mg step-ups?
Gut side effects tend to show up in the first weeks and again after each step-up, then settle. The label says the 2.5 mg starting dose is for getting started, not a maintenance dose, and that the gradual schedule exists to reduce gut side effects. In SURMOUNT-1, the dose rose by 2.5 mg every 4 weeks over a 20-week escalation period, and gut events happened mostly during that time.
| Weeks (label schedule) | Weekly dose | What many people notice |
|---|---|---|
| 1 to 4 | 2.5 mg (starting dose) | Less hunger, early fullness, some nausea |
| 5 to 8 | 5 mg | Nausea or bowel changes may come back for a while |
| Each later step, at least 4 weeks apart | 7.5, 10, 12.5 or 15 mg | A similar, often milder, bump after each increase |
| Maintenance | 5, 10 or 15 mg | Gut symptoms usually ease |
This is what the label describes, not a plan for you. The label tells prescribers to consider how well you tolerate a dose when choosing your maintenance dose and to consider a lower one if needed. If you miss a dose or feel unwell, follow your prescriber and the label. The titration schedules tool shows the full Zepbound and Mounjaro schedules.
How long does nausea last on Zepbound?
For most people nausea is a phase, not a constant. The Zepbound label says most nausea, vomiting and diarrhea happened during dose escalation and decreased over time, and the SURMOUNT-1 trial described most gut events as mild to moderate. Many people notice it most in the days right after their shot. Tracking how you feel each day shows you your own pattern and gives your prescriber something concrete to work with.
Severe gut side effects were less common: 1.7% at 5 mg, 2.5% at 10 mg and 3.1% at 15 mg, vs 1% on placebo.
What helps with tirzepatide side effects?
Smaller meals and stopping at the first sign of fullness help most. Tirzepatide slows how fast your stomach empties, so food stays with you longer than it used to.
- Eat less at a time, and slowly. Leaving food on the plate is fine.
- Protein first. Eggs, yogurt, fish, chicken, tofu or beans at the start of a meal help you get enough protein before you fill up. The protein calculator gives you a daily target.
- Skip the greasiest meals for now. Fried and very rich food is a common nausea trigger.
- Drink steadily through the day, more if you have diarrhea or vomiting. Broth or an electrolyte drink can help.
- Build fiber up slowly for constipation, with more fluid alongside it.
- Stay upright after eating if burping or reflux bother you.
For injection-site redness or itching, rotating between your belly, thighs and upper arms helps. The label notes these reactions were more frequent in people who developed antibodies to tirzepatide (11.3% vs 1%).
Which Zepbound and Mounjaro side effects are serious?
Serious side effects are uncommon, but the label lists warning signs that need fast attention.
Get medical care right away for severe stomach pain that will not go away (with or without vomiting), swelling of the face, lips, tongue or throat, trouble breathing, or signs of dehydration such as very little urine, dizziness or confusion.
- Pancreatitis. Confirmed in 0.2% on Zepbound and 0.2% on placebo in the weight-loss trials, but it can be severe. The label says to stop the medicine if pancreatitis is suspected. Seek care right away.
- Gallbladder disease. Gallstones were reported in 1.1% on Zepbound vs 1% on placebo, and gallbladder inflammation in 0.7% vs 0.2%. Call your clinician about pain in the upper right belly, fever, or yellow skin or eyes.
- Kidney injury from dehydration. Acute kidney injury was reported in 0.5% vs 0.2%. Most reported cases followed nausea, vomiting or diarrhea that led to dehydration. If you cannot keep fluids down, contact your clinician.
- Low blood sugar. In SURMOUNT-2 (type 2 diabetes), low blood sugar was reported in 4.2% on Zepbound vs 1.3% on placebo, and in 10.3% of people also taking a sulfonylurea. Your prescriber may adjust other diabetes medicines.
- Thyroid C-cell tumors (boxed warning). Tirzepatide caused these tumors in rats; it is not known if it does in people. It should not be used if you or a family member has had medullary thyroid cancer or MEN 2. Tell your clinician about a neck lump, trouble swallowing, shortness of breath or lasting hoarseness.
- Allergic reactions. Severe reactions were reported in 0.1% in the trials, and anaphylaxis and angioedema have been reported since approval. Get emergency help.
- Anesthesia and surgery. Tell your care team you take tirzepatide before any procedure that needs anesthesia or deep sedation.
- Birth control pills. Tirzepatide can make oral contraceptives less reliable. The Zepbound label advises a non-oral method, or adding a barrier method, for 4 weeks after starting and for 4 weeks after each dose increase. Ask your prescriber what fits you.
How are Zepbound and Mounjaro different?
Zepbound and Mounjaro contain the same medicine, tirzepatide, made by Eli Lilly, but they are approved for different uses in the US. Zepbound is approved for weight management in adults with obesity, or overweight with a weight-related condition, and for moderate to severe obstructive sleep apnea in adults with obesity. Mounjaro is approved for type 2 diabetes, in adults and in children 10 and older, and to lower the risk of heart attack, stroke and cardiovascular death in adults with type 2 diabetes at high risk.
Both labels start at 2.5 mg once a week and rise in 2.5 mg steps after at least 4 weeks, to a 15 mg maximum in adults. In the Mounjaro diabetes trials, side effect rates were lower than in the weight-loss trials: nausea was 12% to 18% vs 4% on placebo, diarrhea 12% to 17% vs 9%, and decreased appetite 5% to 11% vs 1%. Those trials studied different people with different goals, so the numbers are not a head-to-head comparison.
Mounjaro in Latin America. Zepbound is a US brand. In Mexico and much of Latin America, tirzepatide is sold as Mounjaro, and the approved uses there are set by each country's health regulator. The side effects and warning signs are the same medicine's, so everything above applies. Check your local leaflet and follow your prescriber.
How Morning helps
Morning's shot log follows the dose plan you and your clinician set and reminds you on shot day, and it remembers your last injection sites so you can rotate. Side-effect check-ins show whether nausea or tiredness clusters in the days after a step-up or a shot. The food photo scan counts protein, fiber and water, and Ask Sunny can help with food and side-effect questions, never with dose advice.
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Questions
How long do Zepbound side effects last?
For most people, gut side effects are strongest in the first weeks and after each 2.5 mg step-up, then ease. The Zepbound label says most nausea, vomiting and diarrhea happened during dose escalation and decreased over time.
Are side effects worse at higher Zepbound doses?
Some are. In the label trials, vomiting rose from 8% at 5 mg to 13% at 15 mg, and diarrhea from 19% to 23%. Constipation was highest at 5 mg (17%), and nausea was similar across doses at 25% to 29%.
Does Mounjaro have the same side effects as Zepbound?
Yes. Both are tirzepatide and carry the same warnings, including the boxed thyroid warning. The rates in each label differ because the trials studied different people: adults with type 2 diabetes for Mounjaro and adults with obesity or overweight for Zepbound.
What should I do if I miss a Zepbound dose?
Follow your prescriber and the label. The label has specific missed-dose instructions based on how many days have passed, and your prescriber can tell you how they apply to you.
Does tirzepatide cause hair loss?
Hair loss was reported in 4% to 5% of people on Zepbound vs 1% on placebo, and more often in women (7.1%) than men (0.5%). The label links it to weight loss, and no one in the trials stopped Zepbound because of it.
When should I call my clinician about side effects?
Call right away for severe belly pain that will not go away, vomiting or diarrhea that keeps you from holding fluids down, signs of an allergic reaction, or a lump in your neck. Also tell your clinician if side effects make it hard to eat enough.
Sources
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Educational information, not medical advice. Talk to your clinician about your treatment.