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Tirzepatide and contraceptives: what you need to know?

Birth control pills are the most common contraceptive method used by women today. With the rise of GIP/GLP-1 agonists such as tirzepatide (Mounjaro, Zepbound) and GLP-1 agonists like semaglutide (Ozempic, Wegovy) for type 2 diabetes and obesity, many women wonder if they need to change their birth control method. Tirzepatide may decrease the effectiveness of oral contraceptives, especially when first starting or after each dose increase.

Manufacturer Recommendations

Eli Lilly advises that when you start tirzepatide or after any dose escalation, you should:

  • Continue your oral contraceptive
  • Add a barrier method (for example, condoms) for 4 weeks
  • Or switch to a non‑oral method (IUD, vaginal ring, implant) before starting tirzepatide if you prefer not to use a barrier method

How Tirzepatide Affects Oral Contraceptives

Tirzepatide is a dual agonist of GLP-1 and GIP receptors. It slows gastric emptying, which can reduce the absorption (bioavailability) of oral medications, including contraceptives. A clinical trial showed decreased oral contraceptive bioavailability after the first tirzepatide dose, with less impact after subsequent doses. Common side effects like vomiting and diarrhea can also interfere with pill absorption.

Comparison with Other GLP‑1 Agonists

Tirzepatide is currently the only weight‑loss drug proven in trials to reduce oral contraceptive effectiveness. Other GLP-1 agonists for diabetes or weight management include semaglutide, liraglutide, exenatide, dulaglutide, and lixisenatide.

Pregnancy and Tirzepatide

Weight‑loss medications should not be used during pregnancy. Animal studies of tirzepatide suggested possible fetal harm, though human data are lacking. Poorly controlled diabetes in pregnancy poses its own risks. If you become pregnant or plan to, consult your healthcare provider immediately about tirzepatide use.

Emergency Contraception (Plan B)

Since tirzepatide can affect absorption of oral medications, it may also reduce the effectiveness of emergency contraceptives like levonorgestrel (Plan B), increasing the risk of breakthrough bleeding and unintended pregnancy.

Sources

  • Mounjaro Prescribing Information. FDA. Last updated 11/2024. Accessed Mar 27, 2025.
  • Muller DRP, et al. Effects of GLP-1 agonists and SGLT2 inhibitors during pregnancy and lactation on offspring outcomes: a systematic review. Front Endocrinol. 2023;14:1215356.
  • Skelley JW, Swearengin K, York AL, Glover LH. Impact of tirzepatide and GLP-1 RAs on oral hormonal contraception. J Am Pharm Assoc. 2024;64(1):204-211.e4.