The US Food and Drug Administration warned Thursday that it’s seized “thousands of units” of counterfeit versions of the type 2 diabetes drug Ozempic from the US drug supply chain, and it’s urging suppliers, pharmacies and patients to use caution. Five people have gotten sick in connection with the products, but none of the cases has been serious, the FDA said.

The FDA warns pharmacies, health care systems, wholesalers and patients to double-check their semaglutide products to make sure they are the real thing. One-milligram injectable Ozempic products with the lot number NAR0074 and serial number 430834149057 on the box should not be used.

The agency and drugmaker Novo Nordisk are testing the fakes to determine whether they’re dangerous and to identify what the substance is. The pen label, carton, information for patients and health care professionals, and needles that come with the injectors are also counterfeit, the FDA said. The needles’ sterility can’t be confirmed, so using them could lead to infection.