Tirzepatide Side Effects: Label Rates by Dose, Warnings and When to Get Help
Zepbound adverse reactions by dose
This is Table 1 of the Zepbound prescribing information: two placebo controlled weight loss trials (Studies 1 and 2, 2,519 adults on tirzepatide for up to 72 weeks), reactions reported by at least 2% of people on tirzepatide and more often than on placebo. Percentages are people who reported the reaction at least once. The last column is our arithmetic: the 15 mg rate minus the placebo rate, in percentage points.
| Reaction | Placebo (N=958) | 5 mg (N=630) | 10 mg (N=948) | 15 mg (N=941) | 15 mg minus placebo |
|---|---|---|---|---|---|
| Nausea | 8% | 25% | 29% | 28% | +20 |
| Diarrhoea | 8% | 19% | 21% | 23% | +15 |
| Vomiting | 2% | 8% | 11% | 13% | +11 |
| Constipation | 5% | 17% | 14% | 11% | +6 |
| Abdominal pain | 5% | 9% | 9% | 10% | +5 |
| Indigestion (dyspepsia) | 4% | 9% | 9% | 10% | +6 |
| Injection site reactions | 2% | 6% | 8% | 8% | +6 |
| Fatigue (includes weakness, lethargy, malaise) | 3% | 5% | 6% | 7% | +4 |
| Hypersensitivity reactions | 3% | 5% | 5% | 5% | +2 |
| Belching (eructation) | 1% | 4% | 5% | 5% | +4 |
| Hair loss | 1% | 5% | 4% | 5% | +4 |
| Reflux (GORD) | 2% | 4% | 4% | 5% | +3 |
| Flatulence | 2% | 3% | 3% | 4% | +2 |
| Abdominal distension | 2% | 3% | 3% | 4% | +2 |
| Dizziness | 2% | 4% | 5% | 4% | +2 |
| Low blood pressure | 0% | 1% | 1% | 2% | +2 |
Three things the table shows that the headline numbers hide. The placebo column is not zero: 8% of people on placebo reported nausea and 8% diarrhoea. Constipation is the one common reaction that gets less frequent as the dose rises, from 17% at 5 mg to 11% at 15 mg; the label does not explain why. And counted together, gastrointestinal reactions of any kind were reported by 56% at every dose against 30% on placebo.
Mounjaro adverse reactions by dose
The Mounjaro label pools two placebo controlled trials in adults with type 2 diabetes (SURPASS-1 and SURPASS-5, 718 people on tirzepatide for a mean of 36.6 weeks), and lists reactions seen in at least 5%. The rates are lower than on Zepbound, and the label itself warns that rates from different trials cannot be compared directly.
| Reaction | Placebo (N=235) | 5 mg (N=237) | 10 mg (N=240) | 15 mg (N=241) | 15 mg minus placebo |
|---|---|---|---|---|---|
| Nausea | 4% | 12% | 15% | 18% | +14 |
| Diarrhoea | 9% | 12% | 13% | 17% | +8 |
| Decreased appetite | 1% | 5% | 10% | 11% | +10 |
| Vomiting | 2% | 5% | 5% | 9% | +7 |
| Constipation | 1% | 6% | 6% | 7% | +6 |
| Indigestion (dyspepsia) | 3% | 8% | 8% | 5% | +2 |
| Abdominal pain | 4% | 6% | 5% | 5% | +1 |
Stomach side effects: how common, how severe, how many stop
| Measure | Placebo | 5 mg | 10 mg | 15 mg | Label |
|---|---|---|---|---|---|
| Any gastrointestinal reaction | 30% | 56% | 56% | 56% | Zepbound 6.1 |
| Severe gastrointestinal reaction | 1% | 1.7% | 2.5% | 3.1% | Zepbound 5.2 |
| Stopped because of gastrointestinal reactions | 0.5% | 1.9% | 3.3% | 4.3% | Zepbound 6.1 |
| Stopped because of any adverse reaction | 3.4% | 4.8% | 6.3% | 6.7% | Zepbound 6.1 |
| Any gastrointestinal reaction | 20.4% | 37.1% | 39.6% | 43.6% | Mounjaro 6.1 |
| Severe gastrointestinal reaction | 0.9% | 1.3% | 0.4% | 1.2% | Mounjaro 5.6 |
| Stopped because of gastrointestinal reactions | 0.4% | 3.0% | 5.4% | 6.6% | Mounjaro 6.1 |
Best vendor for tirzepatide right now: Amino Club
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Check price at Amino Club Compare all vendorsHow long the stomach side effects last
Neither label gives a number of days or weeks, and we have not found a trial publication that does, so this page does not invent one. What the sources do say:
- Zepbound label: "The majority of nausea, vomiting, and/or diarrhea events occurred during dose escalation and decreased over time." The Mounjaro label says the same.
- Zepbound label: "The majority of patients who discontinued ZEPBOUND due to adverse reactions did so during the first few months of treatment due to gastrointestinal adverse reactions."
- Both labels: tirzepatide delays gastric emptying, and "The delay is largest after the first dose and this effect diminishes over time."
- SURMOUNT-1, the 72 week trial behind the weight loss doses: the most common adverse events "were gastrointestinal, and most were mild to moderate in severity, occurring primarily during dose escalation" (Jastreboff 2022).
The escalation schedule itself exists for this reason: both labels tell prescribers to follow it "to reduce the risk of gastrointestinal adverse reactions", and the Zepbound label says a lower maintenance dose can be considered if one is not tolerated. The schedule is set out in the tirzepatide dosage guide.
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Open the tirzepatide calculator peptulator.com, the Bureau's independent toolThe boxed warning: thyroid C-cell tumours
"In rats, tirzepatide causes dose-dependent and treatment-duration-dependent thyroid C-cell tumors at clinically relevant exposures. It is unknown whether ZEPBOUND causes thyroid C-cell tumors, including medullary thyroid carcinoma (MTC), in humans as human relevance of tirzepatide-induced rodent thyroid C-cell tumors has not been determined." Zepbound boxed warning; the Mounjaro boxed warning is the same.
Both drugs are contraindicated in anyone with a personal or family history of medullary thyroid carcinoma or with Multiple Endocrine Neoplasia syndrome type 2. The symptoms the label asks people to report are a lump or swelling in the neck, hoarseness, trouble swallowing and shortness of breath. The label also says routine calcitonin blood tests or thyroid ultrasound are of uncertain value for catching it early.
The warnings section, with the label numbers
| Warning | What the labels report | Signs the label says to report |
|---|---|---|
| Acute pancreatitis | Fatal and non-fatal cases seen with GLP-1 drugs and tirzepatide. Zepbound weight trials: 0.2% against 0.2% on placebo. Mounjaro trials: 0.23 against 0.11 patients per 100 years of exposure | Severe stomach pain that may spread to the back, with or without vomiting. The label says to stop the drug if pancreatitis is suspected |
| Gallbladder disease | Zepbound: gallstones 1.1% against 1%, gallbladder inflammation 0.7% against 0.2%, gallbladder removal 0.2% against none. Mounjaro: 0.6% against 0%. Linked to weight reduction | Upper stomach pain, fever, yellowing of the skin or eyes, clay coloured stools |
| Kidney injury from dehydration | Post-marketing reports, some needing dialysis, mostly after nausea, vomiting or diarrhoea. Zepbound trials: 0.5% against 0.2% | Nausea, vomiting or diarrhoea that does not go away. The label asks people to drink fluids to avoid dehydration |
| Low blood sugar with insulin or a sulfonylurea | Zepbound, type 2 diabetes trial: 4.2% against 1.3%, and 10.3% when combined with a sulfonylurea against 2.1% without. Mounjaro with a sulfonylurea: 13.8%, 9.9% and 12.8% on 5, 10 and 15 mg | Dizziness, sweating, confusion or drowsiness, headache, blurred vision, slurred speech, shakiness, fast heartbeat, anxiety or irritability, hunger, weakness |
| Diabetic retinopathy | Temporary worsening reported with rapid improvement in glucose control; people with a history of retinopathy should be monitored. On the Mounjaro label, and on the Zepbound label for people with type 2 diabetes since 08/2026 | Changes in vision |
| Inhaling stomach contents under anaesthesia | Rare post-marketing reports of pulmonary aspiration with GLP-1 drugs during general anaesthesia or deep sedation, despite fasting as instructed | Tell the surgical or procedure team you take tirzepatide before any planned procedure |
| Serious allergic reactions | Anaphylaxis and angioedema reported after approval. Zepbound trials: severe reactions in 0.1% against none on placebo | Swelling of the face, lips, tongue or throat, trouble breathing or swallowing, severe rash or itching, fainting, very fast heartbeat |
| Severe stomach reactions | See the table above. Not recommended in severe gastroparesis | Stomach problems that are severe or will not go away |
Source for every row: section 5 and section 6 of the Zepbound and Mounjaro prescribing information, and the Zepbound medication guide for the symptom lists.
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Build your stack, 2 minutesWhat changed on the label in 2026
The Recent Major Changes box at the top of the current Zepbound label lists "Suicidal Behavior and Ideation (Removed) 02/2026". The warning is no longer in the Zepbound warnings section, and the Wegovy label records the same removal in the same month. The Mounjaro label did not carry that warning. The same Zepbound box shows the severe gastrointestinal reactions warning updated in 02/2026 and the diabetic retinopathy warning added in 08/2026. Mood changes still appear in the medication guide, as one of the listed signs of low blood sugar.
Other effects on the label
- Hair loss: 5%, 4% and 5% against 1% on placebo, associated with weight reduction, 7.1% in women against 0.5% in men, and no one on tirzepatide stopped because of it.
- Heart rate: a mean rise of 1 to 3 beats per minute on Zepbound, against no rise on placebo; 2 to 4 on Mounjaro, against 1 on placebo.
- Low blood pressure: 1.6% against 0.1% on placebo, more often in people already on blood pressure medication (2.2%) and alongside stomach effects and dehydration.
- Fatigue: 5% to 7% against 3%. The causes and fixes are in does tirzepatide make you tired.
- Oral contraceptives: tirzepatide can make them less reliable, so the label advises a non-oral method or an added barrier method for 4 weeks after starting and after each dose increase.
- Alcohol: not covered by the label tables; what is known is in tirzepatide and alcohol.
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When to get help
The Zepbound medication guide asks people to contact a healthcare provider, and in several cases to do so right away, for these:
- Severe stomach pain that does not go away, with or without vomiting, sometimes felt in the back (pancreatitis).
- Pain in the upper stomach, fever, yellowing of the skin or eyes, or clay coloured stools (gallbladder).
- Nausea, vomiting or diarrhoea that does not go away (dehydration and kidney problems).
- Swelling of the face, lips, tongue or throat, problems breathing or swallowing, severe rash or itching, fainting or a very fast heartbeat (serious allergic reaction: emergency care).
- A lump or swelling in the neck, hoarseness, trouble swallowing or shortness of breath (thyroid).
- Changes in vision, for people with type 2 diabetes.
- Signs of low blood sugar, especially with insulin or a sulfonylurea.
For research use vials, the rates above only describe the dose that was intended. Nausea, diarrhoea and vomiting all rise with dose in the Zepbound table, so a drawing or mixing error matters; the arithmetic is in the dosage guide and the mixing step in how to reconstitute peptides.
Key Takeaways
- Digestive effects dominate: on Zepbound, nausea 25 to 29%, diarrhoea 19 to 23%, constipation 11 to 17%, vomiting 8 to 13%.
- Placebo rates are not zero: 8% reported nausea and 8% diarrhoea on placebo.
- Most nausea, vomiting and diarrhoea happened during dose escalation and decreased over time; no label gives a duration in weeks.
- About 93 to 95% of people in the Zepbound trials did not stop because of side effects.
- The boxed warning is thyroid C-cell tumours in rats; human relevance is unknown.
- The suicidal behaviour and ideation warning was removed from the Zepbound label in February 2026.
Frequently Asked Questions
What are the most common side effects of tirzepatide?
Digestive ones. In the Zepbound weight loss trials, across the 5, 10 and 15 mg doses, nausea was reported by 25 to 29% of people (8% on placebo), diarrhoea by 19 to 23% (8%), constipation by 11 to 17% (5%), vomiting by 8 to 13% (2%), and abdominal pain and indigestion by 9 to 10% each. Injection site reactions ran 6 to 8% against 2%.
How long do tirzepatide side effects last?
The labels do not give a number of days or weeks. Both say the majority of nausea, vomiting and diarrhoea occurred during dose escalation and decreased over time, and the Zepbound label says most people who stopped because of side effects did so in the first few months, because of stomach effects. The delay in stomach emptying is largest after the first dose and then diminishes.
Does tirzepatide cause hair loss?
Hair loss is on the Zepbound label: 5%, 4% and 5% on 5, 10 and 15 mg against 1% on placebo. The label says it was associated with weight reduction, was far more common in women (7.1%) than men (0.5%), and that no one on tirzepatide stopped treatment because of it.
What are the serious side effects of tirzepatide?
The labels list a boxed warning for thyroid C-cell tumours seen in rats, plus severe stomach reactions, kidney injury from dehydration, gallbladder disease, pancreatitis, serious allergic reactions, low blood sugar with insulin or a sulfonylurea, worsening diabetic retinopathy in type 2 diabetes, and inhaling stomach contents during anaesthesia or deep sedation.
Does tirzepatide cause thyroid cancer?
It is not known. Tirzepatide caused thyroid C-cell tumours in rats at clinically relevant exposures, and the label says it is unknown whether it causes them, including medullary thyroid carcinoma, in humans. It must not be used by anyone with a personal or family history of medullary thyroid carcinoma or with MEN 2.
When should you call a doctor on tirzepatide?
The Zepbound medication guide lists severe stomach pain that may spread to the back, upper stomach pain with fever, yellow skin or eyes or clay coloured stools, nausea, vomiting or diarrhoea that does not go away, swelling of the face, lips or throat or trouble breathing, a lump in the neck, hoarseness or trouble swallowing, and vision changes in type 2 diabetes.
Is the suicidal thoughts warning still on the Zepbound label?
No. The Recent Major Changes box of the current Zepbound label lists Suicidal Behavior and Ideation as removed in February 2026, and the Wegovy label lists the same removal. The Mounjaro label never carried that warning.
How many people stop tirzepatide because of side effects?
In the two pooled Zepbound weight loss trials, 4.8% on 5 mg, 6.3% on 10 mg and 6.7% on 15 mg stopped permanently because of adverse reactions, against 3.4% on placebo. Stopping because of stomach effects specifically was 1.9%, 3.3% and 4.3% against 0.5%.
Tirzepatide prices by vendor
| Vendor | Vial | Price | Per mg | Ships from | Testing / COA |
|---|---|---|---|---|---|
| Amino Club Readers' pick | 30mg | $59.99 | $2.00 | US | Every batch runs an 8-assay panel at an ISO 17025 lab |
| PSPeptides | 10mg | $54.99 | $5.50 | US | Batch-specific COA on every product page |
| Apollo Peptide Sciences | 20mg | $125.99 | $6.30 | US | Third-party tested every batch |
| Ascension Peptides | 10mg | $105.00 | $10.50 | US | Batch-specific third-party COA |
| Pantheon Peptides | 5mg | $75.00 | $15.00 | US | Every batch tested by an independent lab |
Amino Club list price checked 2026-09-08, the others 2026-09-05; prices change, the link shows the live price. Readers' pick is the vendor Bureau readers have ordered from most this year; code 100 takes 20% off a first order there. PSPeptides prices checked 2026-09-08. Code PEPTIDEBUREAU takes 10% off at PSPeptides and keeps the order counted for the Bureau. Its largest vial is 60mg at $199.99 ($3.33 per mg), which is the cheaper way to buy it there. It is the only vendor here that ships outside the US. Ascension links open the vendor storefront rather than the product page. Bold row is the lowest price per mg among the vendors with a published vial size. Where a vendor sells several vial sizes, the table shows the smallest; larger vials are usually cheaper per mg.
Where the Bureau sources this
The vendors we rank highest for this category on the 2026 scorecard. Amino Club is the one Bureau readers order from most; code 100 takes 20% off a first order there. Research use only.
Amino Club PSPeptides Limitless Life PeptidesSources
- Zepbound (tirzepatide) prescribing information and medication guide, DailyMed, Eli Lilly, revised 08/2026
- Mounjaro (tirzepatide) prescribing information, DailyMed, Eli Lilly, version of 08/2026
- Jastreboff AM et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). N Engl J Med 2022, PMID 35658024
- Wegovy (semaglutide) prescribing information, DailyMed, Novo Nordisk, version of 06/2026 (Recent Major Changes)