Are side effects common with Mounjaro or Wegovy?

Like many prescription medications, Mounjaro and Wegovy can cause side effects, especially during the early stages of treatment or when increasing the dose.

The most common side effect for both medications is nausea.

How common is nausea

  • Mounjaro (tirzepatide): Clinical trials report nausea in around 13–24% of patients, depending on the dose.¹

  • Wegovy (semaglutide): Studies show nausea affects around 35-44% of patients.²³

These gastrointestinal side effects (nausea, bloating, constipation, diarrhoea) are usually mild to moderate and tend to improve over time as your body adjusts.⁴

In most cases, side effects are not severe enough to stop treatment. For example, fewer than 4% of people stopped semaglutide due to gastrointestinal issues in clinical trials.⁴

Many patients on the programme also report that side effects are more noticeable at the beginning of treatment or when increasing their dose.

If you’re experiencing side effects or have concerns about symptoms, please contact your care team or prescriber for support.

 

Footnotes

  1. Mishra, R., Raj, R., Elshimy, G., et al. (2023). Adverse events related to tirzepatide. Journal of the Endocrine Society, 7(4), bvad016. https://doi.org/10.1210/jendso/bvad016
  2. Wharton, S., Calanna, S., Davies, M., et al. (2022). Gastrointestinal tolerability of once-weekly semaglutide 2.4 mg in adults with overweight or obesity, and the relationship between gastrointestinal adverse events and weight loss. Diabetes, Obesity & Metabolism, 24(1), 94–105. https://doi.org/10.1111/dom.14551
  3. Sørensen, M. S., Pottegård, A., Andersen, N. E., Thomsen, R. W., & Lundby, C. (2025). Survey among adult users of semaglutide for weight loss in Denmark: User characteristics, treatment expectations and experienced effects. Diabetes, Obesity & Metabolism, 27(4), 2214–2222. https://doi.org/10.1111/dom.16222
  4. Garvey, W. T., Batterham, R. L., Bhatta, M., Buscemi, S., Christensen, L. N., Frias, J. P., Jódar, E., Kandler, K., Rigas, G., Wadden, T. A., Wharton, S., & STEP 5 Study Group. (2022). Two-year effects of semaglutide in adults with overweight or obesity: The STEP 5 trial. Nature Medicine, 28(10), 2083–2091. https://doi.org/10.1038/s41591-022-02026-4