It's hard not to notice the rise in popularity of weight-loss injections like Wegovy and Mounjaro right now, and a new warning from the UK’s medicines regulator is urging women to think carefully about how contraception can be affected as a result.
The Medicines and Healthcare products Regulatory Agency has issued updated guidance highlighting the potential risks these jabs may pose, both to unborn babies and how they might interfere with the effectiveness of oral contraceptives, particularly in women who are overweight or obese.
As more women explore weight-loss injections like Wegovy and Mounjaro, it's important to be aware of some of the lesser-known guidance around their use. For parents and those hoping to grow their families, understanding how these medications might affect things like contraception and pregnancy can help you make informed, confident choices.
What are GLP-1 medicines?
Originally developed and licensed to treat obesity (and type 2 diabetes in the case of Ozempic), these medications are now also widely used for weight loss. GLP-1 medicines are more commonly known by their brand names such as Wegovy, Mounjaro and Ozempic.
They work by helping people feel fuller for longer, which can lead to reduced calorie intake and weight loss. However, because they affect how the stomach processes food, they can also interfere with the absorption of other medications, like the contraceptive pill, which is why the MHRA has issued specific guidance.
While only available on the NHS to people with a very high BMI, the weight-loss drugs can also be bought privately. These should always be bought from an official pharmacy.
Do weight loss injections affect the pill?
Common side-effects of the jabs, like vomiting and diarrhoea, may mean that the contraceptive pill might not be absorbed properly, potentially leading women to get pregnant on the pill.
The MHRA advises that women should use contraception while taking GLP-1 medications and continue doing so for a set time after stopping treatment - two months for Wegovy and Ozempic, and one month for Mounjaro - before trying to conceive.
The drugs safety body also recommends that women taking Mounjaro alongside an oral contraceptive like the pill should use additional protection, such as condoms, for the first four weeks of using the drug, or consider switching to a longer-term method like the coil or implant.
What's the guidance?
While people should be told this information before they start taking the jabs, there are concerns that the message is not getting through. Advice on contraception appears in patient information leaflets that usually come with the weight-loss injections, but now the MHRA have issued its own guidance which states the drugs should not be taken:
• During pregnancy
• While trying to get pregnant
• During breastfeeding
The MHRA has issued its warning after receiving around 40 pregnancy-related reports through its Yellow Card scheme - a system where the public can report suspected side effects of medicines. Some of these reports involved unintended pregnancies.
Dr Alison Cave, the MHRA’s chief safety officer, explained that animal studies suggest these drugs could harm an unborn baby. However, she noted: "We don't know whether we have the same effects in humans, so much more data is needed to determine that."
Because women of childbearing age are often excluded from clinical trials, there is currently limited safety data available for them.
If you are pregnant, Dr Cave recommends talking to your doctor about stopping the medicine as soon as possible.
Emily Gilbert is the Features & Reviews Editor for Mother&Baby. With a background in both print and digital journalism, she has written extensively on pregnancy, fertility, perinatal mental health, and the best in baby and parenting products. A first-time mum to Theodore, Emily combines her professional expertise with personal experience, offering readers trusted advice and relatable insight. Specialising in product and travel reviews, she stays ahead of the curve on the latest parenting trends and is passionate about showing that life with a little one can still be full of adventure.