MHRA warns women on weight loss and diabetes ‘skinny jabs’ to use effective contraception

The UK’s Medicines and Healthcare products Regulatory Agency (MHRA) has issued new guidance urging women using popular GLP-1 medicines—often dubbed “skinny jabs”—to take extra care with contraception and avoid use during pregnancy or breastfeeding.

The reminder comes amid growing concern that some people are not using these potent prescription medicines safely, particularly when accessed outside regulated healthcare settings.

Medicines such as Ozempic, Mounjaro, Wegovy, Saxenda and Victoza—commonly prescribed for weight management and type 2 diabetes—must not be used while pregnant, trying to conceive, or breastfeeding. The MHRA highlights the lack of safety data during pregnancy and warns that continued use may pose risks to the unborn baby.

“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. “They are not a quick fix to lose weight and have not been assessed to be safe when used in this way.”

Contraception warning for women on Mounjaro

The guidance specifically notes that Mounjaro (tirzepatide) may reduce the effectiveness of oral contraceptives in individuals who are overweight.

In such cases, the MHRA advises using a non-oral form of contraception—such as the coil, implant, or condoms—particularly during the first four weeks of starting treatment or after any dose increase.

“Our guidance offers patients a ‘one stop shop’ for our up-to-date advice on how to use these powerful medicines safely,” added Dr Cave.

Northern Ireland’s Chief Pharmaceutical Officer Professor Cathy Harrison said:

“With use of weight loss medication on the rise in Northern Ireland and across the UK, it is timely that MHRA have issued this reminder to women who use these medications.

“The reminder is clear; do not take GLP-1 medicines if you are pregnant, trying to get pregnant or breastfeeding. If you get pregnant while using them, you should speak to your healthcare professional and stop the medicine as soon as possible.

“All patients, on any form of medication, should read the patient information leaflet, or speak with a healthcare professional as part of the prescribing process.”

Regulator cautions against illegal sales and unregulated use

The MHRA has also reiterated that GLP-1 medicines must only be obtained via a prescription following consultation with a qualified healthcare professional. Selling or sourcing them through beauty salons, social media, or unregulated online sellers is not only dangerous but also illegal.

“Not only does this expose people wanting to lose weight to serious health risks, it is also against the law to sell these medicines in this way,” the agency stated.

Only registered pharmacies can ensure patients receive genuine and properly stored GLP-1 medicines.

Possible side effects and when to seek help

While serious side effects are uncommon, the MHRA guidance highlights symptoms of acute pancreatitis—a potentially serious condition linked with these medicines. Patients are urged to seek immediate medical attention if they experience severe stomach pain that spreads to the back and does not subside.

Additionally, patients should inform their doctor if they are scheduled for surgery and currently taking a GLP-1 medicine.

Summary of key safety advice from MHRA

• Only use GLP-1 medicines if prescribed by a healthcare professional.

• Do not take these medicines during pregnancy, while trying to conceive, or while breastfeeding.

• Mounjaro users who are overweight and use oral contraception should also use a non-oral method.

• Discuss potential side effects and risks with a healthcare professional.

• Never buy GLP-1 medicines from unregulated sources.

• Report side effects or concerns to the MHRA Yellow Card scheme.

• Do not extract leftover medicine from syringes after the four recommended doses.

Understanding GLP-1 medicines

GLP-1 receptor agonists work by mimicking the body’s natural hormones to regulate appetite and blood sugar levels. Some, like Mounjaro, also target a second hormone involved in satiety and glucose control.

While frequently referred to as “weight loss injections” or “skinny jabs” in the media, not all GLP-1 drugs are licensed for weight loss, and their misuse can carry serious health risks.

Further information

Full safety guidance is available on the MHRA website.

The MHRA urges patients and healthcare professionals to familiarise themselves with this information and continue reporting any suspected adverse reactions via the Yellow Card scheme.