Pictured is an example of a falsified pen on top, and a genuine Novo Nordisk pen on the bottom. The Medicines and Healthcare products Regulatory Agency in the United Kingdom says it has received reports that a “very small number” of people were hospitalized after using “potentially fake weight-loss pens.”
CNN  — 

Britain’s health agency is warning the public not to buy pre-filled pens claiming to contain the weight loss drugs Ozempic and Saxenda without a prescription, after a small number of people were hospitalized.

The Medicines and Healthcare products Regulatory Agency said those hospitalized experienced serious side effects, including hypoglycemic shock and coma, indicating that the pens may have contained insulin rather than semaglutide, the medication found in Ozempic. The agency did not include the condition of those hospitalized.

Ozempic is used to treat adults with type 2 diabetes, and is used off-label for weight loss. Saxenda, which contains the drug liraglutide, is authorized in the UK for weight loss. Both medications are only available with a prescription.

More than 350 potentially fake Ozempic pens have been seized since January of this year, according to the MHRA. The agency has also received reports that patients have obtained fake Saxenda pens in the UK through “through non-legitimate routes.”

No fake weight-loss pens were seized before January 2023, the agency says.

The maker of both drugs, Novo Nordisk, told CNN Thursday that it is aware that counterfeit pens are being circulated.

“Novo Nordisk is investigating and reporting every counterfeit case we are made aware to local authorities, in accordance with applicable regulations,” Allison Schneider, a Novo Nordisk spokesperson said in a statement. “Patients can help protect themselves by only buying medicines from legitimate sources and with a prescription from a healthcare professional.”

The MHRA also urged concerned patients to visit that healthcare provider and make sure they are receiving their medication from a legitimate source. All pharmacies in the UK, including those online, must be registered with the General Pharmaceutical Council.

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“We are advising all members of the public not to use any pre-filled weight loss pens they may have bought online and instead to report it to us so that we can investigate and take any necessary action,” Dr. Alison Cave, MHRA Chief Safety Officer, said in a statement Thursday. “Buying products such as Ozempic or Saxenda without a prescription, from illegally trading suppliers, significantly increases the risk of receiving something which is either fake or not licensed for use in the UK.”

Earlier this month, the European Medicines Agency also warned that fake Ozempic pens were being sold throughout the European Union and the UK.

An example of a fake pen posted by German regulators showed several differences from the real product, including different colors, lack of visible Ozempic branding, and additional numbering printed on the fake version. The regulators warned that “it cannot be ruled out that the counterfeit is being sold in Germany.”

Ozempic, and similar medicines used for both diabetes and weight loss, are currently in shortage in both the US and Europe. Novo Nordisk warned in June that a counterfeit Ozempic pen was found in the US, “reportedly purchased at a retail pharmacy.”

CNN Health’s Meg Tirrell contributed to this report.