I got pregnant on tirzepatide — here is what you need to know

You've just found out, what to do in the next 24 hours

Stop taking tirzepatide now, if you have not already. Do not wait for your next scheduled dose or for a follow-up call. The NHS guidance on weight-management injections is unambiguous: tirzepatide is not suitable for use during pregnancy, and the decision to stop does not require clinical permission, it is the clinically appropriate action to take immediately upon discovering a pregnancy.

Contact your GP or midwife as soon as possible, ideally the same day. Tell them you have been taking tirzepatide and roughly when you stopped. They will arrange the early antenatal assessments and can advise on anything else relevant to your particular circumstances. If you have been using a private prescribing service, contact that team too, they need to know treatment has ended, and they can update your clinical record accordingly. Informing everyone involved in your care means nothing falls through the gaps.

One practical note: tirzepatide is supplied as a pre-filled KwikPen, and any remaining pens in the fridge should be disposed of safely through a sharps container or your local pharmacy's medicine return service. Do not feel any pressure to use them up.

Why this can happen, the contraception absorption issue

A number of people who discover they are pregnant while on tirzepatide are surprised, particularly if they were using oral contraception. The reason this can occur is not mysterious. Tirzepatide slows gastric emptying, which means food (and medicines taken by mouth) move through the stomach more slowly than usual. That change in absorption timing can reduce the reliability of the combined pill or progestogen-only pill, especially when treatment is first started or a dose is increased.

UK clinical guidance, as set out on the NHS England weight-management injections page, specifically advises women using oral contraceptives to add a non-oral method (condoms, for example) for the first four weeks of starting tirzepatide and for four weeks after every dose increase. If you were not given that information, or if it got lost in the early weeks of treatment, it is not difficult to see how an unplanned pregnancy might follow. This is a widely known interaction; it is not a failure on your part.

For those wanting to understand the broader picture of how tirzepatide affects fertility and hormones, the question of whether tirzepatide affects the ability to conceive is addressed separately.

What the evidence actually tells us, and where it runs out

Tirzepatide has not been studied in human pregnancies in a formal clinical trial. The Mounjaro Summary of Product Characteristics, available via the electronic Medicines Compendium, notes that animal reproduction studies showed developmental toxicity at exposures relevant to human use, and that the medicine should not be used during pregnancy on that basis. That does not mean a brief exposure in very early pregnancy will necessarily cause harm (the animal data relate to sustained use) but the honest answer is that no one can quantify the human risk with confidence, because the data simply does not exist yet.

What is known is that weight-loss medicines as a class have not historically been tested in pregnancy, and the precautionary principle therefore applies. Your midwife and GP will have seen this situation before; the MHRA's Yellow Card scheme also collects reports of medicine use in pregnancy, which helps build the evidence base over time. If your healthcare team recommends it, a report can be submitted on your behalf or by you directly.

The uncertainty is real, but it is manageable. Most early pregnancies where tirzepatide was taken before the pregnancy was known will be monitored in the normal way, with the prescriber informed and treatment stopped. Deferring to your midwife and GP (rather than extrapolating from forums) is genuinely the right call here, and our guidance on what to do if you are pregnant on tirzepatide covers this ground in more detail if you want a structured overview to take into that first appointment.

Looking ahead: what happens after the pregnancy

Tirzepatide is also not recommended during breastfeeding, and is not suitable for use while actively trying to conceive. Once a pregnancy has concluded and breastfeeding has ended, the question of whether to return to tirzepatide or explore other approaches is one to discuss with your GP and, if appropriate, a specialist. If you found tirzepatide effective before the pregnancy, that history is worth sharing, it is clinically relevant context for whoever reviews your care later.

For anyone who has found out they are pregnant after taking Mounjaro and wants to understand the specific steps involved, that is covered separately alongside the broader question of what tirzepatide use during pregnancy means for ongoing care.

For anyone currently weighing up private treatment options outside pregnancy, our free consultation is the starting point. A GPhC-registered prescriber reads every consultation personally before anything is prescribed, no algorithm, no shortcut. There is more detail on how tirzepatide works as a weight-management medicine and on what private treatment typically costs in the UK for when those questions become relevant again. The treatment overview page sets out the options more broadly.

Right now, though, the priority is your GP and your midwife. Everything else can wait.