In this article
Tirzepatide acts on two gut hormone receptors, GIP and GLP-1, to lower appetite and calorie intake [1]. It also slows your stomach, especially after the first dose [1]. That is a big part of why its common side effects are digestive.
The figures below come from the FDA-approved tirzepatide label for weight management. They pool two 72-week placebo-controlled trials that included 2,519 adults on tirzepatide [1]. The average age was 47, and 63% were women [1]. One of those trials was SURMOUNT-1 [2].
The most common side effects, by dose
| Side effect | Placebo | 5 mg | 10 mg | 15 mg |
|---|---|---|---|---|
| Nausea | 8% | 25% | 29% | 28% |
| Diarrhea | 8% | 19% | 21% | 23% |
| Vomiting | 2% | 8% | 11% | 13% |
| Constipation | 5% | 17% | 14% | 11% |
| Stomach (abdominal) 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% |
| Low blood pressure | 0% | 1% | 1% | 2% |
Two patterns stand out. Vomiting and diarrhea rose with the dose. Constipation did not; it was most common on the lowest dose [1]. And people on placebo reported many of the same things, just less often.
Nausea and other stomach side effects
Digestive side effects were reported by 56% of people on each tirzepatide dose and 30% on placebo [1]. The label says most nausea, vomiting and diarrhea happened during dose escalation and decreased over time [1]. SURMOUNT-1 found the same: most side effects were digestive, mild to moderate, and happened mainly while the dose was going up [2].
Some people stopped because of them. Treatment was stopped for a digestive side effect by 1.9% on 5 mg, 3.3% on 10 mg and 4.3% on 15 mg, compared with 0.5% on placebo [1]. Most people who stopped for any side effect did so in the first few months [1]. Severe digestive side effects were reported by 1.7% to 3.1% across the doses, compared with 1% on placebo [1].
Reported after approval: blocked bowel and severe constipation, including stool that gets stuck [1]. Tirzepatide is not recommended for people with severe gastroparesis [1].
Vomiting and diarrhea can lead to dehydration. Acute kidney injury was reported by 0.5% on tirzepatide and 0.2% on placebo [1]. The patient guide says to drink fluids and to tell your clinician right away about nausea, vomiting or diarrhea that does not go away [1].
Injection site, skin, hair and other effects
- Injection siteRedness, itching, bruising or pain where you inject: 6% to 8%, compared with 2% on placebo.
- Skin reactionsMostly rash or itching. Reported more often in people who developed antibodies to the drug.
- Hair loss7.1% of women and 0.5% of men on tirzepatide. Nobody on tirzepatide stopped because of it.
- Fatigue5% to 7% across doses, compared with 3% on placebo.
- Taste and dry mouthChanged taste in 0.4%; dry mouth or throat in 1%, compared with 0.1% on placebo.
- Heart rateResting heart rate rose by 1 to 3 beats per minute on average.
Source: the tirzepatide label's pooled weight trials [1]
Hair loss is worth a closer look, because it was mostly a women's side effect in the trials. It was reported by 7.1% of women on tirzepatide, compared with 1.3% of women on placebo [1]. The label links it to weight reduction [1]. No one on tirzepatide stopped treatment because of hair loss [1].
Low blood pressure was reported by 1.6% on tirzepatide and 0.1% on placebo. It was more common in people taking blood pressure medicines (2.2%) and was sometimes tied to dehydration [1].
Birth control pills: a warning that matters in perimenopause
Because tirzepatide slows the stomach, it may make oral hormonal birth control less effective. The delay is biggest after the first dose and lessens over time [1].
The label advises women on birth control pills to switch to a non-oral method, or add a barrier method such as condoms, for 4 weeks after starting tirzepatide and for 4 weeks after each dose increase [1]. Birth control that is not taken by mouth should not be affected [1]. If you are in perimenopause and can still become pregnant, raise this with your clinician. Tirzepatide should be stopped if you become pregnant [1].
Serious risks, and the boxed warning
Thyroid C-cell tumors (boxed warning)
In rats, tirzepatide caused thyroid C-cell tumors. It is not known whether it does this in people [1]. Tirzepatide should not be used if you or a family member has had medullary thyroid carcinoma (MTC), or if you have MEN 2 [1]. Tell your clinician about a lump in your neck, trouble swallowing, shortness of breath, or hoarseness that will not go away [1].
Pancreatitis
Inflammation of the pancreas has been seen with tirzepatide and GLP-1 medicines [1]. In the pooled weight trials it was confirmed in 0.2% of people on tirzepatide and 0.2% on placebo [1]. The warning sign is severe stomach pain that will not go away, sometimes spreading to your back. Stop the medicine and call your clinician right away if that happens [1].
Gallbladder problems
Gallstones were reported by 1.1% on tirzepatide and 1% on placebo. Gallbladder inflammation was reported by 0.7% and 0.2%, and gallbladder removal by 0.2% and 0% [1]. The label says these events were associated with weight reduction [1]. Watch for upper stomach pain, fever, yellow skin or eyes, or clay-colored stools [1].
Other warnings on the label
- Serious allergic reactions, including swelling of the face, lips, tongue or throat. In the weight trials, 0.1% had a severe allergic reaction [1].
- Low blood sugar, mainly with insulin or a sulfonylurea. In a trial of people with type 2 diabetes, it affected 4.2% on tirzepatide and 1.3% on placebo, and 10.3% of those also taking a sulfonylurea [1].
- Eye changes in people with type 2 diabetes who have diabetic retinopathy [1].
- Anesthesia and surgery. Food in the lungs has been reported during procedures with anesthesia or deep sedation. Tell every clinician you take tirzepatide before a planned procedure [1].
What helps, according to the label
A slow start. The label starts tirzepatide at 2.5 mg once a week for 4 weeks. The 2.5 mg dose is only for getting started. After that the dose goes to 5 mg and can rise by 2.5 mg at a time, after at least 4 weeks on each dose [1]. The label says this schedule is meant to reduce digestive side effects [1].
A lower dose if needed. If a maintenance dose is hard to tolerate, the label says your clinician may consider a lower one [1]. Maintenance doses are 5 mg, 10 mg or 15 mg [1].
Fluids, and speaking up. Drink fluids if you have nausea, vomiting or diarrhea, and report side effects that are severe or will not go away [1]. Rotate your injection sites with each dose [1].
Comparing options? See semaglutide vs tirzepatide and semaglutide side effects.
Tirzepatide at WarriorBabe Health
WarriorBabe Health offers tirzepatide injections and a tirzepatide microdose injection, prescribed and monitored by licensed clinicians. Ours are compounded by a licensed pharmacy and are not FDA-approved. The FDA does not review compounded drugs for safety, effectiveness or quality before they are sold [3]. It has received reports of side effects that may be tied to compounded tirzepatide taken at doses, or raised on schedules, beyond the FDA-approved label [3]. Follow the dose and schedule your clinician sets, and ask before you change it.
Frequently asked questions
How long do tirzepatide side effects last?
The label says most nausea, vomiting and diarrhea happened while the dose was being raised and decreased over time [1]. If side effects are severe or do not go away, tell your clinician.
Does tirzepatide cause hair loss?
Hair loss was reported by 7.1% of women and 0.5% of men on tirzepatide in the weight trials, compared with 1.3% of women on placebo [1]. The label links it to weight reduction, and no one on tirzepatide stopped treatment because of it [1].
Does tirzepatide affect birth control?
It may make birth control pills less effective. The label advises switching to a non-oral method, or adding a barrier method, for 4 weeks after starting and 4 weeks after each dose increase [1].
Is a higher dose of tirzepatide more likely to cause side effects?
For some side effects, yes. Vomiting rose from 8% on 5 mg to 13% on 15 mg, and diarrhea from 19% to 23% [1]. Constipation went the other way, from 17% on 5 mg to 11% on 15 mg [1].
Who should not take tirzepatide?
The label says not to use it if you or a family member has had medullary thyroid carcinoma, if you have MEN 2, or if you have had a serious allergic reaction to tirzepatide [1]. It is not recommended with severe gastroparesis, and it should be stopped during pregnancy [1].
References
- Eli Lilly and Company. Zepbound (tirzepatide) injection, prescribing information. DailyMed, US National Library of Medicine. Revised 8/2026. dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=487cd7e7-434c-4925-99fa-aa80b1cc776b
- Jastreboff AM, Aronne LJ, Ahmad NN, et al. Tirzepatide once weekly for the treatment of obesity. N Engl J Med. 2022;387(3):205-216. pubmed.ncbi.nlm.nih.gov/35658024/
- US Food and Drug Administration. FDA's concerns with unapproved GLP-1 drugs used for weight loss. www.fda.gov/drugs/drug-alerts-and-statements/fdas-concerns-unapproved-glp-1-drugs-used-weight-loss
This article is for general information. It is not medical advice and does not replace a visit with a licensed clinician who knows your history. Do not start, stop or change a medication without talking to your clinician. If you think you are having a medical emergency, call 911.
