(The Hill) — The Food and Drug Administration (FDA) released an advisory Thursday warning customers not to use counterfeit Ozempic shots found in the drug supply chain.

The administration said it is investigating occurrences of fake semaglutide — the drug found in weight-loss medications such as Ozempic and Wegovy — and said it has already seized thousands of units of the counterfeit product.

The agency advised wholesalers, retail pharmacies, health care practitioners and patients to check the products they receive and to not distribute, sell or use products labeled with NAR0074 and serial number 430834149057, as some counterfeit products may still be available.

The FDA, along with Novo Nordisk, the company that manufactures Ozempic, are testing the 1-milligram semaglutide shots they seized but don’t have information yet about the safety of the drugs.

They found that needles in the samples are fake and the sterility of the needles can’t be confirmed, “which presents an increased risk of infection for patients who use the counterfeit products.”

The pen label, health care professional and patient information and the carton also have been found to be counterfeit.

Only five “adverse events” from the counterfeit group of drugs have been reported, and effects are consistent with reactions other patients have had with the real Ozempic drug.

The FDA recommended retail pharmacies only purchase the weight-loss drug through authorized distributors of Novo Nordisk and for patients to only obtain the drug through state-licensed facilities.