Starting a medication like Mounjaro often brings up questions, and if you are also using contraception, it is completely normal to wonder whether the two might affect each other. While Mounjaro can affect how the pill is absorbed, there are various ways to make sure you stay protected. Here we will guide you through the information and your options moving forward.
How does Mounjaro work?
Mounjaro is a once weekly injection works by mimicking two gut hormones GLP-1 (glucagon-like peptide-1) and GIP (glucose-dependent insulinotropic polypeptide). It helps lower blood sugar and support weight loss by:
- Increasing insulin release when blood sugar is high
- Reducing appetite and helping you feel fuller for longer
- Slowing down the movement of food from your stomach into your intestines (delayed gastric emptying)
It is this last effect of slowing digestion that can sometimes reduce how well oral contraceptives (the pill) are absorbed.
Does Mounjaro affect contraception?
Mounjaro may reduce the effectiveness of oral contraceptives (both the combined pill and the progestogen-only pill). This is due to the medication slowing down how your stomach empties which then can affect the absorption of oral medications.
This makes oral contraceptives less reliable during certain times and the effect is most noticeable when you first start Mounjaro or when your dose is increased. This is why if you are on oral contraceptives while taking Mounjaro, we recommend you to:
- Use a barrier method like condoms or switch to a non-oral method for the initial four weeks after starting Mounjaro
- Do the same for four weeks after every strength/dose increase
- After this time, the pill is expected to work normally again. However, some people prefer to stay on a non-oral method for reassurance
- If you are titrating your dose upwards, it is important to ensure you use barrier method like condoms for the first four weeks after each strength/dose increase. This means that some people may need to use barrier method alongside oral contraceptives for a longer period
Mounjaro side effects and oral contraceptives
Even without Mounjaro, vomiting and diarrhoea can sometimes reduce the effectiveness of the pill because it may not have had time to be fully absorbed.
With Mounjaro, side effects like nausea, vomiting and diarrhoea are common reported side effects, especially in the first few weeks of starting or dose escalation. As tirzepatide (the active drug in Mounjaro) slows down how quickly the stomach empties, this can lead to feelings of fullness and discomfort. On another hand, vomiting is typically associated with higher doses or rapid dose escalation and can accompany nausea in some cases.
If you vomit within three to four hours of taking oral contraceptives, or have severe diarrhoea, your pill may not be effective.
In this situation:
- Follow the “missed pill” advice that comes with your pill pack.
- Use a backup method (such as condoms) until you’re sure you’re protected again, usually one week after side effects subside
- Speak to our team of healthcare professionals if you are unsure
If you had diarrhoea for over 24 hours, keep taking your oral contraceptive as normal alongside barrier method like condoms until your symptoms subside for a week as well.
Which contraceptives are not affected by Mounjaro?
The following methods are not impacted by Mounjaro’s effect on digestion or by sickness/ diarrhoea:
- Contraceptive implant
- Intrauterine device (IUD or coil)
- Contraceptive injection
- Contraceptive patch
- Vaginal ring
- Condoms and other barrier methods
Why is contraception so important with Mounjaro?
Mounjaro is not safe to take during pregnancy as it can potentially harm a developing baby, this is why it is very important to use reliable contraception during treatment.
If you become pregnant while taking Mounjaro, stop taking the medication and contact your prescriber straight away. If you are planning a pregnancy, it is also crucial to let your healthcare provider know in advance.
Can I take Mounjaro with contraceptives?
If you’re taking Mounjaro and using contraception, remember:
- Oral contraceptives may be less reliable when starting or adjusting your dose, or if you vomit or have severe diarrhoea
- Use condoms or a non-oral method for 4 weeks after each dose change
- Consider switching to a non-oral contraceptive for long-term peace of mind
- Avoid pregnancy while on Mounjaro - always seek medical advice if you think you may be pregnant
References
- Medicines.org.uk. (2024). Mounjaro 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, 15 mg solution for injection in pre-filled pen – Summary of Product Characteristics (SmPC). Available at: https://www.medicines.org.uk/emc/product/15481/smpc
- Wise, J. (2024). Does tirzepatide affect the contraceptive pill? BMJ, 389, r1169. doi:10.1136/bmj.r1169. Available at: https://www.bmj.com/content/389/bmj.r1169
- Eli Lilly and Company. (2024). Can adults with type 2 diabetes taking Mounjaro also take oral contraceptives? Lilly Medical Information. Available at: https://medical.lilly.com/us/products/answers/can-adults-with-type-2-diabetes-taking-mounjaro-also-take-oral-contraceptives-200617
- NHS England. (2023). Weight management medicines: Injections. Available at: https://www.england.nhs.uk/ourwork/prevention/obesity/medicines-for-obesity/weight-management-injections/
- GOV.UK. (2024). Women on “skinny jabs” must use effective contraception, MHRA urges in latest guidance. Available at: https://www.gov.uk/government/news/women-on-skinny-jabs-must-use-effective-contraception-mhra-urges-in-latest-guidance
- Faculty of Sexual & Reproductive Healthcare (FSRH). (2023). Patient information: GLP-1 agonists and contraception. Available at: https://www.cosrh.org/Common/Uploaded%20files/documents/Patient-information-GLP-1-agonists-and-contraception.pdf
