Side effects
Tirzepatide side effects: trial rates by dose from the FDA labels
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Short answer
In the Zepbound label's pooled trials, nausea was the most common side effect: 25%, 29% and 28% at 5, 10 and 15 mg vs 8% on placebo. Most nausea, vomiting and diarrhea happened during dose escalation and decreased over time. Hair loss was 4–5% vs 1%; 7.1% of women vs 0.5% of men. As of Oct 19, 2026.
On this page9 sections
| Item | Value | Source |
|---|---|---|
| Nausea, Zepbound 5/10/15 mg vs placebo | 25% / 29% / 28% vs 8% | DailyMed, Aug 28, 2026 |
| Diarrhea, Zepbound 5/10/15 mg vs placebo | 19% / 21% / 23% vs 8% | DailyMed, Aug 28, 2026 |
| Hair loss, Zepbound 5/10/15 mg vs placebo | 5% / 4% / 5% vs 1% | DailyMed, Aug 28, 2026 |
| Hair loss by sex (Zepbound) | 7.1% of women vs 0.5% of men | DailyMed, Aug 28, 2026 |
| Any GI adverse reaction (Zepbound) | 56% at each dose vs 30% on placebo | DailyMed, Aug 28, 2026 |
| Stopped for adverse reactions (Zepbound pool) | 4.8% / 6.3% / 6.7% vs 3.4% placebo | DailyMed, Aug 28, 2026 |
| Nausea, Mounjaro 5/10/15 mg vs placebo | 12% / 15% / 18% vs 4% (different trial pool) | DailyMed, Aug 27, 2026 |
| Boxed warning | Risk of thyroid C-cell tumors (seen in rats) | DailyMed, Aug 28, 2026 |
Also useful: Tirzepatide level plotter.
The best numbers on tirzepatide side effects are in the two FDA labels. Each has an adverse-reaction table built from placebo-controlled trials, broken out by dose. This page reproduces those tables, explains the hair-loss finding, and lists the boxed warning and key warnings as the labels state them. It is not a substitute for the full prescribing information or for your prescriber.
Zepbound side effects by dose
Zepbound’s Table 1 pools two placebo-controlled weight-management trials: Study 1 (SURMOUNT-1) and Study 2 (SURMOUNT-2, which enrolled people with type 2 diabetes). It lists reactions seen in at least 2% of Zepbound patients and more often than with placebo. (DailyMed, Aug 28, 2026)
| Adverse reaction | Placebo (N=958) | 5 mg (N=630) | 10 mg (N=948) | 15 mg (N=941) |
|---|---|---|---|---|
| Nausea | 8% | 25% | 29% | 28% |
| Diarrhea | 8% | 19% | 21% | 23% |
| Vomiting | 2% | 8% | 11% | 13% |
| Constipation | 5% | 17% | 14% | 11% |
| Abdominal pain | 5% | 9% | 9% | 10% |
| Dyspepsia | 4% | 9% | 9% | 10% |
| Injection-site reactions | 2% | 6% | 8% | 8% |
| Fatigue | 3% | 5% | 6% | 7% |
| Hypersensitivity reactions | 3% | 5% | 5% | 5% |
| Eructation (burping) | 1% | 4% | 5% | 5% |
| Hair loss | 1% | 5% | 4% | 5% |
| Gastroesophageal reflux disease | 2% | 4% | 4% | 5% |
| Flatulence | 2% | 3% | 3% | 4% |
| Abdominal distension | 2% | 3% | 3% | 4% |
| Dizziness | 2% | 4% | 5% | 4% |
| Hypotension | 0% | 1% | 1% | 2% |
Some rows group several terms. “Diarrhea” includes frequent bowel movements, “fatigue” includes asthenia, lethargy and malaise, and “hypotension” includes decreased blood pressure and orthostatic hypotension.
Stomach and gut effects
Gastrointestinal reactions dominate. The Zepbound label gives the totals for the same pool. (DailyMed, Aug 28, 2026)
| Measure | Placebo | 5 mg | 10 mg | 15 mg |
|---|---|---|---|---|
| Any GI adverse reaction | 30% | 56% | 56% | 56% |
| Stopped treatment for GI reactions | 0.5% | 1.9% | 3.3% | 4.3% |
| Stopped treatment for any adverse reaction | 3.4% | 4.8% | 6.3% | 6.7% |
The label adds that “the majority of nausea, vomiting, and/or diarrhea events occurred during dose escalation and decreased over time,” and that most people who stopped for adverse reactions did so in the first few months, because of GI reactions. That is the reason the label climbs in 2.5 mg steps with at least 4 weeks on each; the tirzepatide dosage chart shows the ladder, and the titration calculator lays it out on a calendar.
The SURMOUNT-1 paper, which covers Study 1 alone, reported discontinuation for adverse events of 4.3%, 7.1% and 6.2% at 5, 10 and 15 mg vs 2.6% with placebo over 72 weeks. (N Engl J Med, Jul 21, 2022) The label figures above are higher in some arms because they pool two trials.
Does tirzepatide cause hair loss?
The Zepbound label lists hair loss in 5%, 4% and 5% of people on 5, 10 and 15 mg, against 1% on placebo. It gives three more details: (DailyMed, Aug 28, 2026)
| Group | Women | Men |
|---|---|---|
| Zepbound (all doses) | 7.1% | 0.5% |
| Placebo | 1.3% | 0% |
- The label says hair-loss reactions in Zepbound patients “were associated with weight reduction.”
- No Zepbound-treated patients stopped treatment because of hair loss; one placebo patient did.
- The rate did not climb with dose: 5 mg and 15 mg were both 5%.
The Mounjaro label is different. Its clinical-trial table does not include hair loss, and alopecia appears only in the postmarketing section, which gives no rate. (DailyMed, Aug 27, 2026) If you are noticing hair shedding, talk to your prescriber.
Injection-site reactions
Injection-site reactions (bruising, redness, itching, pain, rash) were 6–8% on Zepbound vs 2% on placebo. In the pooled trials they were more frequent in people who developed anti-tirzepatide antibodies (11.3%) than in those who did not (1%). (DailyMed, Aug 28, 2026)
Mounjaro side effects: a different table
The Mounjaro label’s Table 1 comes from a different pool: placebo-controlled trials in adults with type 2 diabetes, with about 235 to 241 people per arm, and a 5% cutoff instead of 2%. (DailyMed, Aug 27, 2026) The two tables are not comparable. The populations, trial lengths and cutoffs differ, so a lower Mounjaro number does not mean Mounjaro is better tolerated.
| Adverse reaction | Placebo (N=235) | 5 mg (N=237) | 10 mg (N=240) | 15 mg (N=241) |
|---|---|---|---|---|
| Nausea | 4% | 12% | 15% | 18% |
| Diarrhea | 9% | 12% | 13% | 17% |
| Decreased appetite | 1% | 5% | 10% | 11% |
| Vomiting | 2% | 5% | 5% | 9% |
| Constipation | 1% | 6% | 6% | 7% |
| Dyspepsia | 3% | 8% | 8% | 5% |
| Abdominal pain | 4% | 6% | 5% | 5% |
In the same Mounjaro pool, any GI reaction occurred in 37.1%, 39.6% and 43.6% at 5, 10 and 15 mg vs 20.4% on placebo, and 3.0%, 5.4% and 6.6% stopped for GI reactions vs 0.4%. Injection-site reactions were 3.2% vs 0.4% on placebo, not broken out by dose. (DailyMed, Aug 27, 2026)
Boxed warning and key warnings
Both labels carry a boxed warning, the FDA’s most prominent kind. (DailyMed, Aug 28, 2026) (DailyMed, Aug 27, 2026)
Warning: risk of thyroid C-cell tumors. In rats, tirzepatide caused dose-dependent and treatment-duration-dependent thyroid C-cell tumors at clinically relevant exposures. The label says it is unknown whether tirzepatide causes thyroid C-cell tumors, including medullary thyroid carcinoma (MTC), in humans. It is contraindicated in people with a personal or family history of MTC or with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). The label lists symptoms of thyroid tumors to report: a mass in the neck, trouble swallowing, shortness of breath, or persistent hoarseness.
The Warnings and Precautions section of the Zepbound label also covers:
- Severe gastrointestinal reactions. Not recommended in severe gastroparesis.
- Acute kidney injury due to volume depletion. The label says to monitor kidney function in people reporting reactions that could lead to it.
- Acute gallbladder disease.
- Acute pancreatitis. Discontinue if suspected. In Studies 1 and 2, adjudicated acute pancreatitis occurred in 0.2% of Zepbound and 0.2% of placebo patients.
- Serious hypersensitivity reactions, such as anaphylaxis and angioedema.
- Hypoglycemia when used with insulin or an insulin secretagogue.
- Diabetic retinopathy complications in people with type 2 diabetes.
- Pulmonary aspiration during general anesthesia or deep sedation. Tell the care team about any planned procedure.
- Never share a KwikPen between people, even with a new needle.
The Mounjaro label lists the same set of warnings in a different order. (DailyMed, Aug 27, 2026) Read the full Medication Guide that comes with your prescription.
What these numbers can and cannot tell you
- They are group rates from trials with set populations and durations. They do not predict what any one person will experience.
- Trial percentages count people who reported a reaction at least once, not how long it lasted.
- The Zepbound and Mounjaro tables come from different trial pools and cannot be compared row by row.
For how long tirzepatide stays in the body after a dose, see the tirzepatide half-life guide and the dose plotter. For approvals and trials, see the tirzepatide hub. If you have side effects that are severe or that worry you, talk to your prescriber.
Frequently asked questions
Does tirzepatide cause hair loss?
- Hair loss is listed in the Zepbound label. In the pooled weight-management trials it was reported by 5%, 4% and 5% of people on 5, 10 and 15 mg vs 1% on placebo. It was more frequent in women (7.1%) than men (0.5%), and the label says hair loss was associated with weight reduction. No Zepbound-treated patients stopped treatment because of it. For Mounjaro, alopecia appears only as a postmarketing report, with no rate.
What are the most common Zepbound side effects?
- Per the Zepbound label, the most common were nausea (25–29% vs 8% placebo), diarrhea (19–23% vs 8%), constipation (11–17% vs 5%) and vomiting (8–13% vs 2%), followed by abdominal pain, dyspepsia, injection-site reactions and fatigue. Ranges cover the 5, 10 and 15 mg arms.
Do tirzepatide side effects go away?
- Both labels say the majority of nausea, vomiting and diarrhea events occurred during dose escalation and decreased over time. The label does not promise that for any one person. If side effects persist or are severe, talk to your prescriber.
Are side effects worse at higher doses of tirzepatide?
- For some, yes. In the Zepbound pool, vomiting rose from 8% at 5 mg to 13% at 15 mg and diarrhea from 19% to 23%. Others did not rise: constipation was highest at 5 mg (17%) and lowest at 15 mg (11%), and nausea was 25%, 29% and 28%.
What is the boxed warning for Zepbound?
- Risk of thyroid C-cell tumors. In rats, tirzepatide caused dose- and duration-dependent thyroid C-cell tumors. The label says it is unknown whether it causes these tumors, including medullary thyroid carcinoma, in humans. Zepbound is contraindicated in people with a personal or family history of medullary thyroid carcinoma or with MEN 2.
Sources
- ZEPBOUND (tirzepatide) injection, for subcutaneous use - Full Prescribing Information, Medication Guide and Instructions for Use (DailyMed SPL set ID 487cd7e7-434c-4925-99fa-aa80b1cc776b, version 40). U.S. National Library of Medicine (DailyMed) / Eli Lilly and Company, Aug 28, 2026. Accessed Oct 19, 2026.
- MOUNJARO (tirzepatide) injection, for subcutaneous use - Full Prescribing Information, Medication Guide and Instructions for Use (DailyMed SPL set ID d2d7da5d-ad07-4228-955f-cf7e355c8cc0, version 40). U.S. National Library of Medicine (DailyMed) / Eli Lilly and Company, Aug 27, 2026. Accessed Oct 19, 2026.
- Tirzepatide Once Weekly for the Treatment of Obesity. N Engl J Med 2022;387(3):205-216 (Jastreboff AM et al.; PubMed PMID 35658024; doi:10.1056/NEJMoa2206038), Jul 21, 2022. Accessed Oct 19, 2026.