NPA and MHRA warn women over weight loss jabs that could undermine contraception

The Medicines and Healthcare products Regulatory Agency (MHRA) has advised women who take GLP-1 medicine for weight loss to be cautious when using contraception.

UK drugs chiefs have warned these injections could causes serious concerns like ineffective contraception, impair unborn babies and could deteriorate the health of pregnant women.

Users of slimming injections like Ozempic and Wegovy are advised to use effective birth control to avoid these potential side-effects.

People using weight-loss injections like Mounjaro, have been advised to ‘double-up’ their contraception doses if they are taking pills. The warning stated that 'Mounjaro may reduce the effectiveness of oral contraceptives in those who are overweight”, adding that safe sex is “especially important for the four weeks after starting Mounjaro and after any dose increase”.

"Pharmacists urge women taking GLP-1 medicines to note this important new guidance from the MHRA,” said Jasmine Shah, Medical Safety Officer at the National Pharmacy Association (NPA).

Shah also pointed out that community pharmacies are having soaring interest for weight loss injections.

Women who conceive while taking these jabs are asked to stop immediately. The same advice applies for breastfeeding mothers as well.

The safety of these injections during the pregnancy period has not been confirmed yet.

“We think that the absorption of oral contraceptive pills may be reduced with GLP-1 drugs which slow down emptying of the stomach, though more research is needed to confirm this,” said Dr Channa Jayasena, a reproductive health expert at Imperial College London.

Currently, more than 40 reports relating to pregnancy among women on the drugs have been reported stated MHRA. While 26 of them were related to Mounjaro, with one unintended pregnancy, other eight cases were related to semaglutide, the active ingredient seen in Ozempic and Wegovy.

The findings of the report that included medics and patients included issues like birth defects, miscarriages and unplanned pregnancies.

In 2024, approximately 35,000 British women of child-bearing age were advised to take these jabs on the NHS in England according to official records.

“Skinny jabs are medicines licensed to treat specific medical conditions and should not be used as aesthetic or cosmetic treatments,” said Dr Alison Cave, MHRA chief safety officer.

"We're pleased that the GPhC has already taken on board concerns expressed by the NPA about a small number of patients who have been able to access weight loss injections without proper consultation or examination of historical medical records” she said.

NPA emphasised the warning from MHRA to prevent the circulation of fake weight loss injections sold on social media or through beauty salons. They have urged the consumers of these drugs to approach their pharmacist for advice, in case of any concerns.

Women are advised to buy weight loss medication from authorized sellers, and to cease the usage immediately in case of pregnancy.