GLP-1 Side Effects: What the Research Says
Understanding the side effect profile of GLP-1 medications is an important part of making an informed decision with your doctor. This article draws directly from the published clinical trial data for semaglutide and tirzepatide — without rounding or extrapolating figures. Individual results vary.
Sources Used in This Article
- Wilding JPH et al. "Once-Weekly Semaglutide in Adults with Overweight or Obesity." NEJM. 2021;384:989–1002. — doi:10.1056/NEJMoa2032183 · PubMed: 33567185
- Jastreboff AM et al. "Tirzepatide Once Weekly for the Treatment of Obesity." NEJM. 2022;387:205–216. — doi:10.1056/NEJMoa2206038
Most Common Side Effects: Semaglutide (STEP 1)
As reported in Wilding et al. (2021), gastrointestinal adverse events were most frequently reported. Individual results vary.
Nausea: 44.2% (semaglutide) vs. 16.0% (placebo)
Diarrhoea: 29.7% vs. 15.9%
Vomiting: 24.5% vs. 6.3%
Constipation: 24.2% vs. 11.1%
Individual results vary. Source: Wilding et al., NEJM 2021.
Discontinuation Due to Adverse Events: Semaglutide (STEP 1)
As reported in Wilding et al. (2021): 7.0% of semaglutide participants discontinued due to gastrointestinal adverse events, compared to 3.1% in the placebo group. Individual results vary.
Most Common Side Effects: Tirzepatide (SURMOUNT-1)
As reported in Jastreboff et al. (2022). Individual results vary.
Nausea: 28–33% across tirzepatide doses vs. 9% placebo
Diarrhoea: 17–22% across doses vs. 11% placebo
Vomiting: 10–15% across doses vs. 2% placebo
Constipation: 11–17% across doses vs. 6% placebo
Individual results vary. Source: Jastreboff et al., NEJM 2022.
Discontinuation Due to Adverse Events: Tirzepatide (SURMOUNT-1)
As reported in Jastreboff et al. (2022): Discontinuation due to adverse events occurred in 4.3% (5 mg), 7.1% (10 mg), and 6.2% (15 mg) of tirzepatide participants, compared to 2.6% placebo. Individual results vary.
How GI Side Effects Are Typically Managed
In both trials, gastrointestinal side effects were most common during the dose-escalation phase and tended to decrease over time. Gradual dose escalation is a standard approach to reduce intensity. Your physician will advise on the appropriate escalation schedule and how to manage any symptoms that arise.
What This Means for Your Program
Your physician at Bunny will discuss the expected side effect profile before prescribing any medication. You will have access to your care team throughout your program. These medications are not appropriate for everyone — your doctor assesses whether the benefit profile is right for your individual situation.
All medical decisions are made solely by licensed healthcare professionals. Medications are prescribed only when medically necessary. GLP-1 medications are not suitable for everyone. Results may vary.
Results vary. Clinical trial results apply only to the FDA-approved branded medication specifically identified and do not apply to compounded medications. All medications must be prescribed by a licensed provider based on medical necessity.