Zepbound Side Effects: What the FDA Label Reports

Summary: Zepbound side effects by the numbers from the FDA label: nausea 25-29%, diarrhea 19-23%, the boxed thyroid warning, and what FDA removed in 2026.

This content is for informational purposes only and is not medical advice. Always consult a qualified healthcare provider before starting, changing, or stopping any medication.

Most Zepbound side effects are digestive, show up while the dose is being raised, and are graded mild to moderate. In the trials behind the FDA label, nausea affected 25% to 29% of people depending on dose, diarrhea 19% to 23%, and constipation 11% to 17%, against placebo rates of 8%, 8%, and 5%. The label also carries a boxed warning about thyroid C-cell tumors seen in rats, plus nine warnings and precautions covering the gallbladder, pancreas, kidneys, and anesthesia risk. One warning that used to be there is now gone: FDA asked manufacturers in January 2026 to strip the suicidal ideation language, and the April 2026 Zepbound label no longer contains it.

Zepbound is tirzepatide, the same molecule sold as Mounjaro for type 2 diabetes. What differs is the population it was studied in and the indications it carries. Zepbound is approved for weight reduction and long-term weight maintenance in adults with obesity or overweight plus at least one weight-related condition, and for moderate to severe obstructive sleep apnea in adults with obesity. The side effect numbers below come from the weight-management trials specifically, which is why they do not match the Mounjaro side effect figures gathered in diabetes trials.

The most common Zepbound side effects, by dose

The label's Table 1 lists reactions that occurred in at least 2% of Zepbound-treated patients and more often than placebo. Percentages are shown for the three maintenance doses studied.

Two patterns are worth reading off that table. Vomiting and diarrhea climb with dose; constipation moves the other way, and is actually most common at 5 mg. And hair loss, which people often assume is anecdotal, is a labeled adverse reaction at roughly four to five times the placebo rate.

Fatigue sits at only 5% to 7% in the trials despite being one of the most discussed complaints among users. Likely contributors beyond the drug itself, including sharp calorie restriction and dehydration, are covered in does Zepbound make you tired.

How long Zepbound side effects last

The label frames gastrointestinal reactions as concentrated during dose escalation. That matches the trial design: Zepbound starts low and steps up at four-week intervals, and each step tends to produce a fresh wave of nausea that settles as the body adapts. Whether and how quickly to escalate is a prescriber's decision, and the label explicitly allows staying at a lower dose longer.

How much these reactions drive people off the drug is measurable. Discontinuation specifically because of gastrointestinal adverse reactions was 0.5% on placebo, 1.9% at 5 mg, 3.3% at 10 mg, and 4.3% at 15 mg. Counting all causes, SURMOUNT-1 reported treatment discontinuation from adverse events in 4.3% at 5 mg, 7.1% at 10 mg, 6.2% at 15 mg, and 2.6% on placebo across 72 weeks. So the large majority of people who start Zepbound and experience nausea do not stop because of it.

For practical management of the nausea itself, see how to relieve nausea from tirzepatide. For how the escalation ladder is structured, see the Zepbound dosing schedule.

The boxed warning: thyroid C-cell tumors

Zepbound carries FDA's most serious warning class. In two-year rat studies, tirzepatide caused dose-dependent and duration-dependent thyroid C-cell tumors at clinically relevant exposures. The label is direct about the limits of that finding: "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."

The practical consequence is a hard contraindication. Zepbound is not to be used by anyone with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2. The label also states that routine calcitonin monitoring or thyroid ultrasound "is of uncertain value" for early detection in people taking it, so surveillance testing is not the workaround.

Serious warnings on the Zepbound label

Beyond the boxed warning, the label lists these warnings and precautions.

Severe gastrointestinal reactions. Sometimes severe, and Zepbound is not recommended in patients with severe gastroparesis.

Acute gallbladder disease. In the pooled weight-management trials, cholelithiasis occurred in 1.1% of Zepbound patients versus 1% on placebo, cholecystitis in 0.7% versus 0.2%, and cholecystectomy in 0.2% versus none on placebo. Rapid weight loss of any cause raises gallstone risk, which complicates attributing this to the drug directly.

Acute pancreatitis. In the pooled trials, adjudicated acute pancreatitis occurred in 0.2% of Zepbound patients and 0.2% of placebo patients. That is one of the more useful numbers on the label, because it shows no separation from placebo in the controlled data, even though pancreatitis is reported after marketing.

Acute kidney injury from volume depletion. Driven by dehydration from vomiting and diarrhea rather than a direct kidney effect. Postmarketing reports include cases requiring hemodialysis.

Hypersensitivity reactions. Immediate reactions occurred in 2.1% of Zepbound patients versus 0.4% on placebo; non-immediate reactions in 3.5% versus 2.7%.

Hypoglycemia. Low blood sugar was uncommon in people without diabetes, at 0.3% versus none on placebo. In the trial arm of patients with type 2 diabetes it reached 4.2% versus 1.3%. Risk rises when Zepbound is combined with insulin or a sulfonylurea.

Diabetic retinopathy complications. Applies to people with type 2 diabetes and a retinopathy history, where rapid glucose improvement can temporarily worsen the eye disease.

Pulmonary aspiration under anesthesia. Because tirzepatide delays gastric emptying, there have been rare postmarketing reports of aspiration during procedures requiring general anesthesia or deep sedation, in patients who had followed fasting instructions. The label is candid that "available data are insufficient" to say whether pausing the drug or extending the fast would help, and instructs patients to tell providers about Zepbound before any planned procedure.

Never share a pen between patients, even with a changed needle, because of bloodborne pathogen risk.

What FDA removed from the label in 2026

Earlier Zepbound labeling contained language about suicidal behavior and ideation, carried over from an FDA safety evaluation opened in 2023. FDA's January 2024 communication reported that its initial review of clinical trial data did not find an association, while noting that the small number of events left real uncertainty in the estimate.

That evaluation is now closed. In a January 13, 2026 letter, FDA requested that application holders remove the suicidal ideation and behavior information from GLP-1 receptor agonist labeling, naming Zepbound, Wegovy, and Saxenda. The basis was a meta-analysis of 91 placebo-controlled trials across GLP-1 development programs, which did not identify an increased risk. The current Zepbound label reflects the change, listing "Suicidal Behavior and Ideation (Removed) 02/2026" under recent major changes.

This is a label change, not a claim that mood effects never occur. It means the controlled evidence did not support a warning. Anyone experiencing new or worsening depression or suicidal thoughts on any medication should contact their prescriber.

Side effects reported after approval

The postmarketing section lists reactions reported in real-world use, where frequency cannot be calculated and causation is not established. These include hemorrhagic and necrotizing pancreatitis, sometimes fatal; ileus; intestinal obstruction; severe constipation including fecal impaction; anaphylaxis and angioedema; pulmonary aspiration; and acute renal failure or worsening chronic renal failure, sometimes requiring hemodialysis.

Ileus deserves a specific mention because it is frequently discussed online as though it were a trial finding. It is not. It appears only in postmarketing experience, which means it was reported by clinicians after approval rather than observed at a measurable rate in the controlled studies.

One interaction worth knowing about

The label carries a specific instruction for people using oral hormonal contraceptives: switch to a non-oral method, or add a barrier method, for four weeks after starting Zepbound and for four weeks after each dose increase. Delayed gastric emptying can reduce absorption of oral contraceptives during those windows. This is easy to miss and has obvious consequences.

Does the sleep apnea indication change the risk picture?

Zepbound's second indication came from the SURMOUNT-OSA program. The adverse event profile there looked like the weight-management trials: predominantly gastrointestinal and mostly mild to moderate. In Study 1, diarrhea occurred in 26.3% on tirzepatide versus 12.5% on placebo, nausea in 25.4% versus 10.0%, and vomiting in 17.5% versus 4.2%. Discontinuation from adverse events was low in both arms and, in Study 2, slightly more common on placebo than on tirzepatide.

How Zepbound compares to semaglutide

Cross-trial comparison is limited, because the drugs were mostly studied separately in different populations. What the labels do show is that both carry the rodent thyroid C-cell boxed warning and the same gallbladder, pancreatitis, kidney, and aspiration warnings. The differences are in the numbers, not the kinds of events. See Zepbound vs Wegovy for what is and is not comparable, and our tirzepatide side effects page for the molecule-level view.

Frequently asked questions

What is the most common side effect of Zepbound? Nausea, at 25% to 29% depending on dose, versus 8% on placebo. Diarrhea is close behind at 19% to 23%.

Do Zepbound side effects go away? The label describes gastrointestinal reactions as concentrated during dose escalation, and discontinuation rates suggest most people continue through them. There is no published figure for the exact proportion whose nausea fully resolves, so anyone promising a specific timeline is going beyond the evidence.

Does Zepbound cause hair loss? It is a labeled adverse reaction, reported in 4% to 5% of Zepbound patients versus 1% on placebo. Rapid weight loss independently triggers telogen effluvium, so the trials cannot separate drug effect from weight-loss effect.

Is Zepbound linked to suicidal thoughts? FDA reviewed 91 placebo-controlled trials and did not identify increased risk, and in January 2026 requested removal of the warning from Zepbound, Wegovy, and Saxenda labels. The current label no longer contains it.

Who should not take Zepbound? The label contraindicates it in anyone with a personal or family history of medullary thyroid carcinoma, anyone with MEN 2, and anyone with known serious hypersensitivity to tirzepatide or its excipients. It is also not recommended in severe gastroparesis. Whether Zepbound is appropriate in pregnancy, kidney disease, pancreatitis history, or alongside insulin is a prescriber's judgment, not something to decide from an article.

This article summarizes what the FDA-approved Zepbound prescribing information and published trials report. It is not medical advice. Dosing, escalation, and whether Zepbound is suitable for you are decisions for a licensed prescriber who knows your history.