Women using popular weight-loss and diabetes medications known as "skinny jabs" have been urgently advised by the UK’s Medicines and Healthcare products Regulatory Agency (MHRA) to use effective contraception while on these drugs, and in some cases, for up to two months after stopping before attempting to conceive. This alert comes amid growing concerns about the safety of these drugs during pregnancy and reports of unintended pregnancies despite contraceptive use.
The MHRA’s warning, issued in early June 2025, specifically highlights the risks associated with glucagon-like peptide-1 receptor agonists (GLP-1 RAs) such as Wegovy, Ozempic, Saxenda, Victoza, and particularly Mounjaro. These drugs work by mimicking hormones that regulate appetite and blood sugar levels, helping users feel full and thereby promoting weight loss. Mounjaro, which contains tirzepatide, is unique among these as it affects a second hormone involved in metabolism and appetite control.
One of the key concerns raised by the MHRA is that Mounjaro may reduce the effectiveness of oral contraceptives, especially in overweight individuals. This is due to the drug’s impact on the digestive system, including slowing stomach emptying and causing side effects like nausea, vomiting, and diarrhoea, which can interfere with the absorption of the contraceptive pill. The regulator advises that women taking Mounjaro who use oral contraception should also use an additional barrier method such as condoms or switch to a non-oral contraceptive method like an intrauterine device (coil) or implant. This additional protection is especially critical during the first four weeks after starting Mounjaro and following any dose increase.
The MHRA has received over 40 reports relating to pregnancies among women using these medications, with 26 reports associated with Mounjaro, including at least one unintended pregnancy. Reports linked to semaglutide-based drugs (Ozempic and Wegovy) number eight, and nine relate to liraglutide-based drugs (Saxenda and Victoza), with some cases involving birth defects, miscarriages, and unplanned pregnancies. These reports have fueled concerns over the safety of these drugs during pregnancy, although conclusive human data remains limited.
Dr. Alison Cave, the MHRA’s chief safety officer, stressed the importance of using these medicines only as prescribed for specific medical conditions. "Skinny jabs are medicines licensed to treat specific medical conditions and should not be used as aesthetic or cosmetic treatments. They are not a quick fix to lose weight and have not been assessed to be safe when used in this way," she said. Dr. Cave urged patients to have thorough discussions with healthcare professionals before starting these drugs and to carefully read patient information leaflets.
The MHRA also strongly warns against purchasing weight-loss injections from unregulated sources such as beauty salons or social media platforms, which is illegal and potentially dangerous. The only safe way to obtain these medications is through legitimate pharmacies and healthcare providers.
Experts in reproductive health have weighed in on the issue. Dr. Channa Jayasena, a consultant in reproductive endocrinology at Imperial College London, explained that GLP-1 drugs slow stomach emptying, which likely reduces the absorption of oral contraceptives. He noted, "Obesity reduces fertility in women. So, women with obesity taking GLP-1 drugs are more likely to get pregnant than before they lost weight." He added that while the exact harm of these drugs during pregnancy is unknown, other weight-loss methods like surgery have been linked to increased miscarriage risk, underscoring the need for effective contraception.
Professor Rebecca Reynolds, an expert in metabolic medicine at the University of Edinburgh, highlighted findings from animal studies indicating potential risks such as low birthweight and skeletal abnormalities, though she emphasized that more human research is needed to confirm these effects.
The MHRA’s guidance also reminds patients to be vigilant for symptoms of acute pancreatitis, a rare but serious side effect characterized by severe stomach pain radiating to the back. Immediate medical attention is advised if these symptoms occur.
Real-life stories underscore the importance of this alert. Natasha Major, a 26-year-old woman, began taking Mounjaro to lose weight before planning to conceive in the future. Despite using the contraceptive pill, she discovered she was pregnant six weeks after starting the drug. "I have polycystic ovaries and can’t get pregnant easily, so it was a big shock," she said. Upon learning of her pregnancy, Natasha stopped taking Mounjaro immediately and has since had an early scan confirming a viable pregnancy.
Similarly, women worldwide have reported unexpected pregnancies while on these drugs, sometimes referred to online as "Ozempic babies," reflecting the growing popularity and widespread use of these medications beyond their originally intended patient groups. In 2024 alone, approximately 35,000 British women of childbearing age were prescribed GLP-1 drugs on the NHS, though the true number is likely higher due to private purchases.
Jasmine Shah, medication safety officer at the National Pharmacy Association, emphasized the need for patient safety amid unprecedented demand for weight-loss injections. "Medicines are not like ordinary goods for sale; they must be handled with great care because they have the power to harm as well as to heal," she said. Shah also warned about the risks posed by counterfeit or unregulated products sold online or in non-medical settings.
The MHRA’s comprehensive guidance serves as a crucial resource for patients and healthcare providers, offering clear advice on the safe use of these powerful medicines. It underscores that while GLP-1 drugs can be effective tools for managing obesity and diabetes, they require careful management, especially concerning contraception and pregnancy planning.
As the popularity of weight-loss jabs continues to surge, with more than a million Britons now using them and Mounjaro leading in demand, this alert highlights the vital importance of informed use and medical supervision. Women taking these medications are urged to consult healthcare professionals about contraception options, understand potential side effects, and report any adverse reactions through the MHRA’s Yellow Card scheme.
Ultimately, these drugs are not a magic bullet for weight loss, nor are they cosmetic treatments. They are potent medicines that must be used responsibly to safeguard women’s health and the wellbeing of their future children.
