Zepbound Side Effects: How Common They Are, How Long They Last, and the Serious Warnings

The most common side effects of Zepbound are nausea, diarrhea, vomiting, constipation, abdominal pain, indigestion, injection site reactions, fatigue, allergic reactions, burping, hair loss and acid reflux.1 Each was reported by at least 5% of people taking Zepbound.1

Source: Zepbound label, Table 1, pooled Studies 1 and 2.1

Overall, 56% of people on each Zepbound dose had a gastrointestinal side effect, against 30% on placebo.1 Between 4.8% and 6.7% stopped Zepbound because of side effects, against 3.4% on placebo.1

Stomach side effects usually show up while the dose is being raised, which in the trials meant the first months of treatment.1 The label states that most nausea, vomiting and diarrhea occurred during dose escalation.1 Most people who stopped because of side effects did so in the first few months.1

Tirzepatide reaches its peak level in the blood about 24 hours after an injection, with a range of 8 to 72 hours.1 The label does not give a typical day of onset for each side effect.

For most people, nausea, vomiting and diarrhea fade with time: the label says these events decreased over time after the dose-escalation period.1 The step-up schedule exists for this reason: doses rise slowly to reduce the risk of stomach side effects.1 Details are in our Zepbound dosage guide.

The label does not give a fixed number of days or weeks. Tirzepatide has a half-life of about 5 to 6 days, so each dose stays active for most of the week.1 Severe or persistent stomach symptoms should be reported to a prescriber, because they can lead to dehydration and kidney injury.1

Yes, hair loss is a listed side effect: 4% to 5% of people on Zepbound reported it, against 1% on placebo.1 The label links it to weight reduction rather than to the drug directly.1

It was much more common in women. In the pooled trials, 7.1% of women on Zepbound reported hair loss, against 0.5% of men.1 No one taking Zepbound stopped treatment because of it.1

Hair shedding after a large weight loss is a known pattern called telogen effluvium. The American Academy of Dermatology lists losing 20 pounds or more as a trigger, notes that shedding usually shows up a few months after it, and says hair tends to regain its normal fullness within six to nine months.3

Hair loss (alopecia) is listed in the Mounjaro label among side effects reported since approval, but not among its most common side effects.2 Mounjaro's most common side effects are nausea, diarrhea, decreased appetite, vomiting, constipation, indigestion and abdominal pain.2 Post-approval reports are voluntary, so their frequency cannot be reliably estimated.2

Fatigue is a listed side effect: 5% to 7% of people on Zepbound reported it, against 3% on placebo.1 The label's fatigue category includes weakness, lethargy and feeling unwell.1

Dizziness (4% to 5% versus 2%) and low blood pressure (1% to 2% versus 0%) were also more common on Zepbound.1 Low blood pressure was more frequent in people taking blood pressure medicines, and was linked to stomach side effects and dehydration.1 Tiredness can also be a sign of low blood sugar, mainly in people also taking insulin or a sulfonylurea.1

Neither headache nor insomnia appears in the Zepbound label's table of side effects, which lists effects reported by at least 2% of people and more often than on placebo.1 That does not mean no one experiences them, only that the trials did not show them above the placebo rate.

Headache has been reported in a different setting: overdoses. In an alert on compounded semaglutide, the FDA listed headache and migraine among the events seen in patients who drew the wrong dose from a vial.5 Anyone using compounded vials should check their units carefully; see our guide to compounded tirzepatide.

Diarrhea affected 19% to 23% of people on Zepbound and constipation 11% to 17%, against 8% and 5% on placebo.1 Diarrhea rose with dose, while constipation was most common at 5 mg.1

Since approval, there have been reports of severe constipation, including fecal impaction, and of intestinal blockage (ileus and intestinal obstruction).1 Ongoing diarrhea or vomiting can cause dehydration, which the label links to acute kidney injury.1

An FDA review published in January 2026 found no increased risk of anxiety, depression or suicidal thoughts with GLP-1 drugs, including Zepbound.4 The review pooled 91 placebo-controlled trials with about 108,000 patients.4 The FDA then asked makers of Zepbound, Wegovy and Saxenda to remove the suicidal behavior warning from their labels.4

The FDA still advises patients to tell their clinician about new or worsening depression, suicidal thoughts, or any unusual changes in mood or behavior.4 The 988 Suicide & Crisis Lifeline offers support 24 hours a day.4

Zepbound carries a boxed warning: tirzepatide caused thyroid C-cell tumors in rats, and it is unknown whether it does in humans.1 It must not be used by anyone with a personal or family history of medullary thyroid carcinoma or with Multiple Endocrine Neoplasia syndrome type 2.1 Report a lump in the neck, trouble swallowing, shortness of breath or lasting hoarseness.1

The label's other warnings:1

• Severe stomach reactions. Reported by 1.7% to 3.1% on Zepbound versus 1% on placebo. Not recommended with severe gastroparesis.
• Kidney injury. Mostly in people dehydrated from nausea, vomiting or diarrhea.
• Gallbladder disease. Gallbladder inflammation was reported in 0.7% on Zepbound versus 0.2% on placebo.
• Pancreatitis. Stop Zepbound and seek care for severe abdominal pain that may spread to the back.
• Allergic reactions. Including anaphylaxis and swelling of the face or throat.
• Low blood sugar. Mainly with insulin or a sulfonylurea.
• Diabetic retinopathy. Can worsen in people with type 2 diabetes.
• Anesthesia. Tell your care team before any procedure, because a slow-emptying stomach raises the risk of inhaling its contents.

Zepbound may also reduce the effect of birth control pills for 4 weeks after starting and after each dose increase.1 Our safety hub covers these warnings across all GLP-1 drugs.

Do side effects get worse with each dose increase? The label reports most nausea, vomiting and diarrhea during the dose-escalation period, decreasing over time.1 Several side effects, including vomiting, were more common at higher doses.1

Are injection site reactions serious? They were reported by 6% to 8% on Zepbound, and included bruising, redness, itching, pain or rash at the site.1 Rotating sites is covered in how to inject Zepbound.

Does Zepbound cause hair loss in men? Rarely in the trials: 0.5% of men on Zepbound reported it, against 7.1% of women.1

Is Zepbound safe long term? Zepbound is approved for long-term use to maintain weight reduction.1 The trials ran for up to 72 weeks for weight and 52 weeks for sleep apnea.1 See what is Zepbound for the full safety overview.

If side effects or price are shaping your choice, compare Wegovy vs Zepbound and Mounjaro vs Zepbound, or check Zepbound cost and Mounjaro cost. Pharmacy-made vials carry their own risks; read compounded tirzepatide vs Zepbound before looking at compounded tirzepatide providers. To find a prescriber who can monitor side effects, see how to get tirzepatide online or our best GLP-1 options.

This article is for information only and is not medical advice. Report side effects to your clinician, and seek emergency care for severe abdominal pain, signs of an allergic reaction or trouble breathing. Zepbound is a prescription drug with real risks and side effects.