The Medicines and Healthcare products Regulatory Agency (MHRA) said it was reviewing safety data on a class of drugs known as GLP-1 receptor agonists.

It includes Ozempic, sold by Danish drugmaker Novo Nordisk, which contains the active ingredient semaglutide and is approved to treat Type 2 diabetes but has gained popularity as a "miracle" weight-loss aid.

The agency said although Ozempic was not approved for weight loss, "it is commonly used off-label for that purpose" in the UK.

The review also includes the company's Saxenda, which contains the active ingredient liraglutide and is approved as a weight-loss treatment.

Saxenda is Novo's older GLP-1 drug and has a lower effectiveness than its newer obesity treatment, Wegovy, which contains semaglutide. The agency approved the drug for weight-loss treatment in 2021, but it has not yet launched in the UK.

"Patient safety is our top priority," said Dr Alison Cave, MHRA chief safety officer.

"We will carefully consider all available evidence and communicate any further advice to patients and healthcare professionals as appropriate."

GLP-1 receptor agonists were originally developed to treat Type 2 diabetes and mimic the gut hormone that suppresses appetite, promoting a feeling of fullness.

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EU also investigating Ozempic and Saxenda

The review comes two weeks after similar action by the European Union after Iceland's health regulator flagged three cases of patients thinking about suicide or self-harm.

It is also investigating GLP-1 drugs for possible risk of thyroid cancer.

The MHRA said its review would consider safety data including adverse drug reactions reported by patients and clinicians to the MHRA and other medicines regulators.

It received five reports of suspected adverse drug reactions associated with "suicidal and self-injurious" behaviour in patients who took Ozempic or Wegovy between 2020 and 6 July this year.

It also received 12 similar reports involving Saxenda between 2010 and 6 July.

The MHRA said the fact symptoms occur after use of a medicine is not proof of causation.