Short answer: In the label's two placebo-controlled weight trials, the most common Zepbound side effects were nausea (25% to 29% vs 8% on placebo), diarrhea (19% to 23% vs 8%), constipation (11% to 17% vs 5%) and vomiting (8% to 13% vs 2%). Most stomach side effects happened while the dose was being raised and eased over time. Zepbound has a boxed warning about thyroid C-cell tumors.
What Zepbound is approved for: Zepbound is approved, with a reduced-calorie diet and more physical activity, to reduce excess body weight and keep it off in adults with obesity, or with overweight and at least one weight-related condition, and to treat moderate to severe obstructive sleep apnea in adults with obesity (section 1). The label says not to use it with other tirzepatide products or any GLP-1 receptor agonist.
Source
ZEPBOUND (tirzepatide) injection, prescribing information and Medication Guide. Eli Lilly. DailyMed, version published September 2, 2026. DailyMed setid 487cd7e7-434c-4925-99fa-aa80b1cc776b
WARNING: RISK OF THYROID C-CELL TUMORS
In rats, tirzepatide caused thyroid C-cell tumors. It is not known whether Zepbound causes these tumors, including medullary thyroid carcinoma (MTC), in people. Zepbound must not be used by anyone with a personal or family history of MTC or with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). Symptoms to report include a neck lump, trouble swallowing, shortness of breath or lasting hoarseness.
These are the label's own numbers from the Adverse Reactions section. Where the label compares with placebo (a dummy treatment), both columns are shown, so you can see how much more often a reaction happened on Zepbound.
| Adverse reaction | Placebo (N=958) % | Zepbound 5 mg (N=630) % | Zepbound 10 mg (N=948) % | Zepbound 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 | 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 |
Two placebo-controlled trials with 2,519 adults with obesity or overweight on Zepbound for up to 72 weeks. Some rows group related terms: diarrhea includes frequent bowel movements; abdominal pain includes discomfort and tenderness; injection site reactions include bruising, redness, itching, pain and rash; fatigue includes weakness, lethargy and malaise; hypotension includes low and orthostatic blood pressure.
Stomach and gut reactions overall: 56% on each Zepbound dose vs 30% on placebo. Stopping because of them: 1.9% (5 mg), 3.3% (10 mg) and 4.3% (15 mg) vs 0.5% on placebo. Most nausea, vomiting and diarrhea happened during dose escalation and decreased over time.
Stopping treatment for any side effect: 4.8%, 6.3% and 6.7% on 5, 10 and 15 mg vs 3.4% on placebo, mostly in the first few months and mostly for stomach reactions.
Hair loss was linked to weight reduction and was more common in women: 7.1% of women vs 0.5% of men on Zepbound (1.3% vs 0% on placebo). No one on Zepbound stopped treatment because of it.
Gallbladder: gallstones 1.1% vs 1% on placebo, gallbladder inflammation 0.7% vs 0.2%, gallbladder removal 0.2% vs none. Acute kidney injury 0.5% vs 0.2%. Low blood pressure 1.6% vs 0.1%.
In people with type 2 diabetes (Study 2), low blood sugar under 54 mg/dL was reported in 4.2% on Zepbound vs 1.3% on placebo; with a sulfonylurea it was 10.3% vs 2.1% without one (section 5.7).
The Warnings and Precautions part of the label lists these. Each line gives the label's heading and what it means in plain words.
Risk of thyroid C-cell tumors. The boxed warning risk: thyroid tumors seen in rats. Not for people with a personal or family history of MTC or with MEN 2.
Severe stomach and gut reactions. Severe gut reactions were reported in 1.7% to 3.1% of people on Zepbound vs 1% on placebo. Zepbound is not recommended for people with severe gastroparesis.
Kidney injury from fluid loss. Kidney injury, sometimes needing dialysis, has been reported, mostly after fluid loss from nausea, vomiting or diarrhea. Kidney function is checked in people with these reactions.
Gallbladder disease. Zepbound is linked to more gallbladder disease, such as gallstones and gallbladder inflammation. If gallstones are suspected, the label calls for gallbladder tests.
Acute pancreatitis. Inflammation of the pancreas, including fatal cases, has been seen with this drug class. Signs include severe stomach pain that will not go away, sometimes spreading to the back. If it is suspected, Zepbound is stopped.
Serious allergic reactions. Anaphylaxis and angioedema have been reported after approval. If a serious allergic reaction happens, Zepbound is stopped.
Low blood sugar. Zepbound lowers blood sugar and can cause hypoglycemia, more so with insulin or a sulfonylurea. The label says lowering the dose of those medicines may reduce the risk.
Diabetic eye disease. In people with type 2 diabetes, fast blood sugar improvement has been linked to temporary worsening of diabetic retinopathy.
Breathing in stomach contents during anesthesia. Zepbound slows stomach emptying. Rare cases of pulmonary aspiration under general anesthesia or deep sedation have been reported with this drug class; tell the care team before any procedure.
Never share a KwikPen. A Zepbound KwikPen must never be shared, even with a new needle, because of the risk of passing on blood-borne infections.
From the Medication Guide that comes with Zepbound:
Dose Track has a side-effect log. Each entry records the symptom, a severity (none, mild, moderate, severe or life-threatening), the date and an optional note, and can be tied to a specific dose or logged on its own. The history screen shows what you logged over time, which makes it easier to tell your prescriber when a reaction started and whether it is easing. The app records what you enter; it does not judge whether a symptom is serious. For anything on the label's call-your-doctor list, call your doctor.
This page is what the FDA label says, in plain words. It is not medical advice. Follow your prescriber, and ask them or your pharmacist about anything here.