Using Mounjaro When Pregnant: What the Evidence Says

You've just found out you're pregnant and you're taking Mounjaro

This is probably the scenario that brought you here, and the most important thing first: stop taking Mounjaro and contact your GP or midwife today. Not when the next pen arrives. Not at your next scheduled check-in. Today.

The reason isn't that tirzepatide is proven to harm a developing pregnancy. The honest answer is that nobody knows, there are no adequate, well-controlled trials in pregnant women, and that gap in evidence is itself the clinical basis for the recommendation. Animal studies at high doses did show reproductive toxicity, which is enough for regulators to say the risk cannot be ruled out. When the potential downside is unknown and the upside of continuing a weight-management medicine during pregnancy is low, the guidance is unambiguous: stop the medicine.

Once you've spoken to your GP or maternity team, they'll assess whether any monitoring is needed and what happens next with your weight management. Your prescriber at any regulated online pharmacy, including at our pharmacy at nume, should also be informed so your records are updated and no repeat treatment is issued.

The NHS tirzepatide medicines page summarises this guidance clearly for patients and is a good first reference alongside calling your GP.

If you're planning to get pregnant: what to do before you conceive

Planning ahead gives you more options. The Mounjaro SmPC and NHS guidance both advise that women who want to become pregnant should stop tirzepatide before trying to conceive, allowing a sufficient washout period. The exact duration to discuss with your prescriber is based on the medicine's half-life and its effects on nutrition during active weight loss, this is a conversation for a clinician who knows your full history, not a general rule to apply yourself.

Weight management before pregnancy matters. Obesity is associated with higher risks of gestational diabetes, pre-eclampsia and other complications, so the goal isn't to abandon weight management, it's to find an approach that's safe during pregnancy. Your GP or a specialist service can help you plan this transition.

If you're currently on treatment and thinking about pregnancy in the near future, raise it at your next clinical review. If you're a nume patient, our aftercare team is available seven days a week and can connect you with your prescriber to plan next steps properly.

You can read more about the broader considerations of taking Mounjaro during pregnancy in our dedicated guide, which covers the regulatory position in more detail.

Contraception on Mounjaro: a step many people miss

Tirzepatide slows gastric emptying, the rate at which your stomach empties into the gut. This matters for oral contraceptives because it can reduce how much of the pill is absorbed into your bloodstream. The practical result is that your usual oral contraceptive pill may be less reliable during the early weeks of Mounjaro treatment and after each dose increase.

NHS guidance is specific: women using oral contraceptives should add a non-oral method of contraception, such as condoms, for the first four weeks of starting Mounjaro and for four weeks after every dose increase. This applies at every step up the titration schedule, not just at the start. NHS England's weight management injections guidance covers this alongside advice on HRT for women on tirzepatide.

There is no equivalent evidence of reduced pill effectiveness for semaglutide (Wegovy), so this is specific to tirzepatide rather than a blanket GLP-1 class effect. If you're considering whether Mounjaro or Wegovy better suits your situation (including contraceptive considerations) our Mounjaro overview explains how the two medicines differ.

Worth noting: this contraception guidance applies during active treatment. If you've stopped Mounjaro with the intention of conceiving, the washout period discussed with your prescriber is the relevant timeframe, not the four-week oral contraceptive rule.

Breastfeeding and the period after pregnancy

Mounjaro is not recommended during breastfeeding. There is no human data on whether tirzepatide passes into breast milk, and given what is known about its mechanism, the precautionary position is to avoid it while nursing. This isn't a judgement about breastfeeding choices, it's the same logic as the pregnancy guidance: unknown risk, with no clinical benefit during this period that outweighs the uncertainty.

For women who have given birth and are not breastfeeding, the question of restarting weight management treatment is one for your GP or prescriber once you're ready. Post-pregnancy is also a period when weight-related health conditions may need reassessment, and a fresh consultation makes sense before restarting any prescription medicine.

Our general FAQs cover some of the common questions about restarting treatment, and anyone considering Mounjaro for the first time or after a break can start a free consultation with our GPhC-registered prescribers, who review every case individually. The process involves ID and weight verification alongside a clinical assessment, a real prescriber reads your answers, not automated software.

If you want to understand the full clinical picture before your consultation, our detailed guide on Mounjaro and pregnancy goes further on the regulatory background and what to expect from that GP conversation. Many patients also find it helpful to read our guidance on whether you can have Mounjaro when pregnant, our overview of Mounjaro when pregnant, and our page answering whether you can take Mounjaro when pregnant, which together cover the most common questions we receive on this topic. The MHRA's guidance on GLP-1 medicines is also available on GOV.UK for anyone who wants the regulator's position directly.