Most Common Side Effects of Mounjaro (tirzepatide)

Mounjaro® (tirzepatide) is a newer med mainly for type 2 diabetes, but people are also using it to lose weight. It works well, but it does have side effects, mostly in your stomach and intestines. This article looks at the most common problems people have when taking Mounjaro, based on what studies and regulators say.

Keywords:

Tirzepatide. Mounjaro. Side effects. GLP-1. Type 2 diabetes.

What’s This About?

Tirzepatide, also known as Mounjaro®, hits two targets in your body: glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). This makes it better at controlling blood sugar and weight than older meds (ELI LILLY, 2023, p. 4). But, as more folks use it, there are worries about side effects, mainly if they’re not getting advice from a doctor.

How It Works and Why It Causes Problems

Tirzepatide slows down how quickly food leaves your stomach, makes you feel full, and helps your body release insulin when your blood sugar is up (FDA, 2022, p. 12). These same things can cause the main side effects. The National Sanitary Surveillance Agency says that the most often reported bad reactions are related to the digestive system (ANVISA, 2025, p. 1).

Stomach and Gut Issues

The most typical side effects from Mounjaro are feeling sick to your stomach, throwing up, diarrhea, and constipation. Studies show that feeling sick usually happens at the start and gets better as your body gets used to the med (FRIAS et al., 2021, p. 589). These symptoms are linked to the slower emptying of your stomach, which makes you feel full sooner.

Diarrhea and constipation are also fairly common, depending on how much of the drug you’re taking. Sometimes, these problems can make people stop taking the med, especially if they’re not slowly upping the dose (FDA, 2022).

Other Reported Side Effects

Besides stomach issues, some people feel tired, dizzy, and have less of an appetite. Though not as common, low blood sugar can happen, mainly if you’re taking tirzepatide with other diabetes meds like insulin (ELI LILLY, 2023).

Rarely, there have been reports of pancreatitis and gallbladder issues, so doctors need to keep an eye on this. Experts say that serious events are rare, but need close medical watching (FRIAS et al., 2021, p. 592).

The Bottom Line

Mounjaro seems to be safe if used how doctors tell you to. The usual side effects mostly involve the stomach and tend to go away. However, using it without guidance can raise the chance of more serious problems. So, it’s key for doctors to prescribe it carefully and keep checking on patients.

eferences (ABNT – NBR 6023)

ANVISA. Anvisa approves the use of the drug Mounjaro (tirzepatide). Brasília, 2025. Available at: https://www.gov.br/anvisa. Accessed on: Jan. 19, 2026.

ELI LILLY AND COMPANY. Mounjaro (tirzepatide): prescribing information. Indianapolis, 2023. Available at: https://www.lilly.com. Accessed on: Jan. 19, 2026.

FDA – FOOD AND DRUG ADMINISTRATION. FDA approves novel, dual-targeted treatment for type 2 diabetes. Silver Spring, 2022. Available at: https://www.fda.gov. Accessed on: Jan. 19, 2026.

FRIAS, J. P. et al. Efficacy and safety of tirzepatide in type 2 diabetes. New England Journal of Medicine, v. 385, n. 6, p. 503–515, 2021. Available at: https://www.nejm.org. Accessed on: Jan. 19, 2026.