Explosive demand and high prices for Novo Nordisk and Eli Lilly's weight loss and diabetes drugs have fueled a criminal effort to package autoinjector pens containing other substances, such as insulin, with branding and batch numbers that make them look like Novo's Ozempic.

If patients suspect they have bought a fake version of Ozempic or another drug, they can search the internet for the associated batch number to see if the World Health Organization or any national health authorities have flagged it.

Patients can typically find these batch, or lot, numbers on both legitimate and fake versions of Ozempic or other similar pen-based drugs like Novo's Wegovy in two places: on the outside of the box it is packaged in and on the label of the autoinjector itself.

Novo and Lilly have also published guides to help patients identify suspected fake versions of their drugs in other ways and report them.

The WHO this year flagged three batch numbers - LP6F832, NAR0074 and MP5E511 - that have been linked to fake Ozempic in Brazil, the U.S. and Austria respectively, a Reuters review of documents and regulator announcement shows.

The organization sent an alert to health regulators in July 2023 flagging MP5B060 - which has been found on fake Ozempic pens in at least 10 countries - as well as MP5A370 and MP5D600, which have both been found in Guatemala, according to an announcement from the country's health regulator.