Women who are taking or considering taking Mounjaro, listen up. If you take the oral contraceptive pill (such as the combined pill, or progestogen only pill/ “mini pill”) there is important guidance to be aware of.
In June 2025, the UK’s medicines regulatory board, MHRA are urging women taking medical weight loss injections to use “effective contraception” to prevent pregnancy. They warn that tirzepatide, the active ingredient in Mounjaro, has been found to reduce the effectiveness of the oral contraceptive pill in some women.
In fact, some women on Mounjaro have found themselves pregnant despite taking the pill.
This is an issue as the MHRA have advised that medicines must not be taken during pregnancy, while trying to get pregnant, or during breastfeeding. This is because there is not enough safety data to know whether taking the medicine could cause harm to the baby.
Before beginning any medical weight loss treatments, it is vital that you understand how they can interact with your contraception. The National Health Service (NHS) have released guidance on the effectiveness of oral contraception when taking injectable therapies like Mounjaro.
At Bodyline, we prescribe medical weight loss treatments within fully supported programmes, providing guidance and advice throughout a weight loss journey. We’ve put together a handy explainer on using Mounjaro and its impact on the oral pill.
What is Mounjaro?
Mounjaro is the brand name for tirzepatide, a prescription injection initially developed to manage type 2 diabetes but now also used to support weight loss.
It’s part of a newer class of medications known as GLP-1/GIP receptor agonists, which means it mimics the effects of two hormones that help regulate blood sugar and appetite. Mounjaro is only available via prescription and is typically offered as part of a comprehensive medical weight loss programme.
It is prescribed to strict eligibility criteria. According to the National Institute of health and Care Excellence (NICE), Mounjaro can only be prescribed to those with a Body Mass Index (BMI) of 30kg/m2 and above, classifying them as obese, or 27kg/m2 (overweight) with a weight related health condition.
How does Mounjaro work?
Mounjaro works by mimicking both GLP-1 (glucagon-like peptide-1) and GIP (glucose-dependent insulinotropic polypeptide), two gut hormones that help control blood sugar, curb appetite, and slow the rate at which your stomach empties food into the intestines.
This delayed gastric emptying is a key reason why people feel fuller for longer and, as a result, tend to eat less and lose weight while using Mounjaro.
I’m on the pill, will Mounjaro impact my contraception?
If you use the oral contraceptive pill, it’s important to know that Mounjaro can affect its effectiveness.
Because Mounjaro significantly delays gastric emptying, it can reduce how much of the pill is absorbed into your bloodstream, especially during the first four weeks after starting Mounjaro or following any dose increase.
Clinical studies have shown that a single 5 mg dose of tirzepatide can decrease the overall exposure to oral contraceptives by about 20%.
Due to this, both the manufacturer, Eli Lilly and regulatory bodies like MHRA recommend using a barrier method (like condoms) or switching to a non-oral contraceptive for four weeks after starting Mounjaro and for four weeks after any increase in dose.
Alternatively, there are other GLP-1 weight loss injections and medical weight loss treatments that do not interact with oral contraception. Get in touch with us to find out more.
How does the contraceptive pill work?
The oral contraceptive pill contains synthetic versions of the hormones estrogen and progesterone. These hormones prevent pregnancy by stopping ovulation, where the ovaries release an egg. They also thin the lining of the uterus, reducing the chances of a fertilized egg implanting.
If Mounjaro reduces the exposure to the hormones, the effects of the pill are not as concentrated and therefore could be reduced, increasing likelihood of pregnancy.
Should I use Mounjaro if I want to get pregnant?
Mounjaro is not recommended if you are planning to become pregnant. There is limited safety data on its use in pregnancy and animal studies suggest some potential risks to the developing baby.
If you are planning to conceive, for the health of you and your future baby, you should stop Mounjaro and allow a washout period of at least one month before trying to get pregnant. A washout period is the time it takes for your body to naturally rid the medication from your system.
If you become pregnant while on Mounjaro, it’s important to speak with your prescriber and healthcare provider as soon as possible and cease taking the medication.
Dr Morgan Toerien is a weight health, and wellness practitioner at Bodyline:
“The important thing is that if people are planning to have children, they should come off their GLP-1s prior to planning a pregnancy because we don’t know about the safety. This reiterates the importance of using effective contraception. If one wants to make sure that there’s no ambiguity, then barrier methods or non-oral methods are probably better. But with most GLP-1s, the evidence shows if you’re established on a normal GLP-1 that isn’t tirzepatide, you generally are quite safe unless you’ve changed the dose.”
Mounjaro and fertility
Research from an early clinical review says GLP-1 receptor agonists have been shown to improve ovulation rates and regulation in the menstrual cycle in women, and improved sperm motility and male sex hormones in men, largely due to its reduction of the negative impacts that obesity has on fertility. More human studies are needed to confirm this further, but doctors are seeing an increase in so-called “Ozempic babies”. Dr Morgan Toerein explains why:
“When a patient starts to lose weight, at some point they might have an increase in their fertility, which they didn’t know about. Whereas in the past, they’ve not conceived, all of a sudden as their body and their general state of health is improving, the patient can accidentally fall pregnant without expecting it. In my view, that is probably one of the biggest factors we can account for when we see people falling pregnant unexpectedly while using GLP-1s.”
But because of the lack of data scientists have of using Mounjaro prior to pregnancy, in pregnancy, and breastfeeding, along with the potential for harm that is suggested in animal studies, effective contraception beyond the pill is strongly advised while using Mounjaro.
Bodyline’s holistic approach
Using Mounjaro as part of a weight loss programme with Bodyline provides access to comprehensive support and guidance. Our specialised medical wellness clinics offer personalised care, regular consultations, and ongoing monitoring to ensure the safe and effective use of Mounjaro.
Healthcare professionals at our clinics assess your individual needs, provide guidance and advice based on your individual situation, exploring the medications that will work for you in your situation. We offer a range of medications that can be used alongside the contraceptive pill, so with our expertise and support, you can embark on a successful weight loss journey.
If you’re considering Mounjaro as a tool for effective weight loss and use the pill, or you’re planning a pregnancy, why not speak to our specialist weight health team to find the safest and most effective approach for your situation.
Get in touch today, call us on 0800 995 6036 or fill in an online contact form for a call back.
Contact Bodyline today to find out more about our safe and effective weight loss programmes and range of treatment options.
"*" indicates required fields