Zepbound side effects: how common they are, when they happen and what to watch for

What are the most common Zepbound side effects?

Zepbound is tirzepatide, a once-weekly injection that acts on both the GIP and GLP-1 receptors. In the US it is approved for weight reduction and long-term maintenance in adults with obesity, or overweight plus a weight-related condition, and for moderate to severe obstructive sleep apnea in adults with obesity. Its prescribing information, revised in August 2026, reports side effects from two 72-week placebo-controlled trials: SURMOUNT-1 (adults without diabetes) and SURMOUNT-2 (adults with type 2 diabetes).

Side effect	Placebo	5 mg	10 mg	15 mg
Nausea	8%	25%	29%	28%
Diarrhea	8%	19%	21%	23%
Constipation	5%	17%	14%	11%
Vomiting	2%	8%	11%	13%
Belly pain	5%	9%	9%	10%
Indigestion	4%	9%	9%	10%
Injection-site reactions	2%	6%	8%	8%
Fatigue	3%	5%	6%	7%
Allergic-type reactions	3%	5%	5%	5%
Burping	1%	4%	5%	5%
Hair loss	1%	5%	4%	5%
Acid reflux (GERD)	2%	4%	4%	5%
Dizziness	2%	4%	5%	4%

Zepbound US label, Table 1. Gas, bloating and low blood pressure were also more common than on placebo, at lower rates.

A few Zepbound-specific patterns stand out:

• Constipation was most common at the lowest maintenance dose (17% at 5 mg), while vomiting rose with the dose.
• Most allergic-type reactions were skin reactions such as rash or itching. They, and injection-site reactions, were more frequent in people who developed antibodies to tirzepatide.
• Hair loss was mainly reported by women (7.1% vs 0.5% of men) and was linked to weight reduction. Nobody on Zepbound stopped treatment because of it.

When do Zepbound side effects start, and do they go away?

Timing follows the dose ladder. Zepbound starts at 2.5 mg once a week for four weeks. That is a starting dose, not a maintenance dose. The dose then rises in 2.5 mg steps, each after at least four weeks, to a maintenance dose of 5, 10 or 15 mg (10 or 15 mg for sleep apnea).

The label says most nausea, vomiting and diarrhea occurred during dose escalation and decreased over time. Most people who stopped because of side effects did so in the first few months. Overall, 4.8–6.7% stopped Zepbound because of side effects, compared with 3.4% on placebo.

In practice, the days after a new dose step tend to be the bumpiest. If a maintenance dose isn’t tolerated, the label lets your prescriber consider a lower one; that’s their call, not a do-it-yourself change. Our dose escalation guide explains how the steps work.

What are the serious side effects of Zepbound?

These are uncommon, but the label asks prescribers to warn about each one:

• Thyroid C-cell tumors (boxed warning). Tirzepatide caused these tumors in rats; whether it does in humans is unknown. Zepbound must not be used with a personal or family history of medullary thyroid carcinoma or MEN 2. Report a neck lump, trouble swallowing, shortness of breath or lasting hoarseness.
• Severe stomach problems. Severe GI reactions affected 1.7–3.1% vs 1% on placebo. Zepbound isn’t recommended with severe gastroparesis. After approval, ileus, bowel obstruction and severe constipation with fecal impaction have been reported.
• Kidney injury from dehydration. Most reports involved fluid loss from nausea, vomiting or diarrhea, and some people needed dialysis. In trials it was 0.5% vs 0.2%.
• Gallbladder disease. Gallbladder inflammation (0.7% vs 0.2%) and gallstones (1.1% vs 1%) were linked to weight loss.
• Pancreatitis. Confirmed cases were 0.2% in both groups in the weight trials, but serious and sometimes fatal pancreatitis has been seen with tirzepatide and GLP-1 medicines.
• Serious allergic reactions. Anaphylaxis and angioedema have been reported after approval.
• Low blood sugar. In SURMOUNT-2, 4.2% had glucose below 54 mg/dL vs 1.3% on placebo, rising to 10.3% in people also on a sulfonylurea. Your doctor may lower insulin or sulfonylurea doses.
• Diabetic eye disease. Fast improvement in blood sugar can temporarily worsen diabetic retinopathy.
• Anesthesia. Zepbound slows stomach emptying, and rare aspiration under anesthesia or deep sedation has been reported with GLP-1 medicines. Tell every care team about Zepbound before a procedure.
• Lower blood pressure, faster pulse. Low blood pressure affected 1.6% vs 0.1%, more often in people on blood pressure medicines; heart rate rose by 1–3 beats per minute on average.

Zepbound may also make birth control pills less reliable. The label suggests switching to a non-oral method, or adding a barrier method, for four weeks after starting and after each dose increase. See GLP-1s, birth control and pregnancy. A former label warning on suicidal thoughts and behavior was removed in February 2026, but tell your doctor about any mood changes that worry you.

What helps with Zepbound side effects?

We cover each problem in its own guide, so here is the short version:

• Nausea: smaller, slower, lower-fat meals, stopping at the first sign of fullness, and sipping fluids between meals. Expert consensus supports these steps. See what helps GLP-1 nausea.
• Constipation: add fiber gradually, drink enough and keep moving; ask a pharmacist before laxatives. See GLP-1 constipation relief.
• Low appetite: build small meals around protein first, as in what to eat on a GLP-1.
• Hair shedding: usually tied to the pace of weight loss; see GLP-1 hair loss.
• Drinking: alcohol overlaps with nausea, dehydration and low blood sugar; see alcohol and GLP-1s.
• Injection-site reactions: the label says to rotate sites with each weekly dose.

Never skip, delay or split a dose on your own to dodge side effects. Raise it with your prescriber instead.

When should you call a doctor about Zepbound side effects?

Get urgent care for:

• Severe belly pain that won’t go away, with or without vomiting, sometimes spreading to the back
• Swelling of the face, lips, tongue or throat, trouble breathing or swallowing, or fainting
• Vomiting or diarrhea that stops you keeping fluids down, or signs of dehydration

Call your doctor promptly for:

• Upper-belly pain, fever, yellow skin or eyes, or clay-colored stools (possible gallbladder trouble)
• Low blood sugar symptoms such as shakiness, sweating or confusion if you use insulin or a sulfonylurea
• Vision changes if you have type 2 diabetes
• A lump or swelling in your neck, or hoarseness that persists
• Any side effect that is severe or doesn’t settle

What should you log on Zepbound?

A simple record makes appointments faster and dose decisions easier:

• Dose and date, which step you’re on, and the injection site
• Each side effect, its severity, and how many days after the injection it peaked
• Fluids, meals and bowel habits on rough days
• Weight trend, plus glucose readings if you have diabetes
• Upcoming procedures that need anesthesia or sedation

GLPMate’s Zepbound tracker logs doses with reminders and maps injection sites, and the side-effect tracker records severity so you can export a doctor report before your next visit. This article is educational only and not medical advice; talk to your doctor about any side effect that concerns you.

FAQ

FAQ

What are the most common side effects of Zepbound?

In the pooled SURMOUNT-1 and SURMOUNT-2 trials, the most common were nausea (25–29% vs 8% on placebo), diarrhea (19–23% vs 8%), constipation (11–17% vs 5%) and vomiting (8–13% vs 2%). Indigestion, belly pain, injection-site reactions, fatigue, burping, reflux and hair loss were also more common than on placebo.

How long do Zepbound side effects last?

The label says most nausea, vomiting and diarrhea happened during dose escalation and decreased over time, and most people who stopped because of side effects did so in the first few months. Each 2.5 mg step can bring a few rougher days. If a dose isn't tolerated, your prescriber can consider a lower maintenance dose.

Does Zepbound cause hair loss?

Hair loss was reported in 4–5% of people on Zepbound vs 1% on placebo, far more often in women (7.1%) than men (0.5%). The label links it to weight reduction, and no one in the trials stopped Zepbound because of it. Mention persistent shedding to your doctor.

When should I call a doctor about Zepbound side effects?

Get help right away for severe belly pain that won't go away (sometimes spreading to the back), signs of a serious allergic reaction, or vomiting or diarrhea that stops you keeping fluids down. Call your doctor for upper-belly pain with fever or yellow skin or eyes, vision changes if you have diabetes, or a lump in your neck.