Tirzepatide Side Effects: What the Trials Actually Report

What are the most common tirzepatide side effects?

The most common tirzepatide side effects reported in SURMOUNT-1 were gastrointestinal, led by nausea, diarrhea, constipation, and vomiting (Jastreboff et al., NEJM 2022; doi:10.1056/NEJMoa2206038).

SURMOUNT-1 was a 72-week phase 3 trial in 2,539 adults with obesity, or overweight with a weight-related condition, who did not have type 2 diabetes (Jastreboff et al., NEJM 2022). Across the studied doses, most adverse events were mild to moderate in severity, and the gastrointestinal symptoms below were the events that separated tirzepatide from placebo most clearly.

The ranges below reflect what the published study reported across its 5 mg, 10 mg, and 15 mg dose groups. This is educational, not a prescription or a personal recommendation.

Values are approximate and rounded from the trial's reported rates by dose (nausea 24.6, 33.3, and 31.0 percent; diarrhea 18.7, 21.2, and 23.0 percent; constipation 16.8, 17.1, and 11.7 percent; vomiting 8.3, 10.7, and 12.2 percent).

Are tirzepatide side effects dose-related?

Yes: SURMOUNT-1 reported that gastrointestinal side effects generally became more frequent at higher doses (Jastreboff et al., NEJM 2022).

The trial studied once-weekly doses of 5 mg, 10 mg, and 15 mg, reached through a gradual escalation that started lower and stepped up over several weeks (Jastreboff et al., NEJM 2022). This escalation design is one reason the rates above are shown as ranges: nausea and vomiting, for example, tended to sit toward the higher end at the higher doses. These are research-reported figures, not a dose suggestion. What dose, if any, is appropriate is a decision for a qualified clinician.

When do tirzepatide side effects tend to happen?

Trial data reported that gastrointestinal side effects were most common while the dose was being raised, and were less prominent once a stable dose was reached (Jastreboff et al., NEJM 2022).

Because the SURMOUNT-1 protocol increased the dose in steps, the nausea, vomiting, and related symptoms were concentrated in the early weeks of each step-up rather than spread evenly across the full 72 weeks (Jastreboff et al., NEJM 2022). The SURPASS-2 diabetes trial described the same timing, with gastrointestinal events occurring mainly during the escalation period for both tirzepatide and semaglutide (Frias et al., NEJM 2021).

How many people stopped tirzepatide because of side effects?

Discontinuation due to adverse events was low in SURMOUNT-1, at about 4 to 7 percent across the studied doses compared with about 3 percent on placebo (Jastreboff et al., NEJM 2022).

By dose, treatment discontinuation for adverse events was reported at 4.3 percent (5 mg), 7.1 percent (10 mg), and 6.2 percent (15 mg), versus 2.6 percent on placebo (Jastreboff et al., NEJM 2022). In other words, most participants who reported side effects stayed in the trial. Serious adverse events were reported in a low share of participants and were broadly similar between the tirzepatide and placebo groups. This is trial-level data and does not predict any individual's experience.

How does tirzepatide compare with semaglutide for side effects?

In the head-to-head SURPASS-2 trial, tirzepatide and semaglutide both produced a gastrointestinal-predominant side-effect profile, with nausea, diarrhea, and vomiting among the most common events for each (Frias et al., NEJM 2021; doi:10.1056/NEJMoa2107519).

SURPASS-2 studied adults with type 2 diabetes, so its population differs from SURMOUNT-1, but the pattern was consistent. The trial reported nausea in about 17 to 22 percent of the tirzepatide groups versus about 18 percent for semaglutide, diarrhea in about 13 to 16 percent versus about 12 percent, and vomiting in about 6 to 10 percent versus about 8 percent (Frias et al., NEJM 2021). Both were described as mostly mild to moderate. For a fuller side-by-side, see the comparison page linked below.

What happens after stopping tirzepatide?

Stopping is not a side effect, but the SURMOUNT-4 trial reported that participants who withdrew from tirzepatide tended to regain a substantial share of the weight they had lost (Aronne et al., JAMA 2024).

In SURMOUNT-4, after a 36-week open-label lead-in on tirzepatide, participants were randomized either to continue or to switch to placebo. The group that stopped regained weight over the following months, while the group that continued kept and added to their earlier reduction (Aronne et al., JAMA 2024). This matters for expectation-setting: the trial data describe an ongoing therapy, and outcomes after withdrawal differed from outcomes during treatment. Whether and how to start or stop is a clinical decision.

Do these trial findings apply to me?

Not necessarily: SURMOUNT-1 reports averages across a defined trial population, and personal risk can differ (Jastreboff et al., NEJM 2022).

Peptara Labs supplies materials for research use and does not provide medical advice, dosing instructions, or safety guarantees. The figures on this page are here so you can read the primary evidence with clearer context, then take specific questions about suitability, risk, and dose to a qualified clinician.