The U.S. Food and Drug Administration is warning wholesalers, retail pharmacies, healthcare workers and patients that counterfeit Ozempic may still be in the drug supply chain.
The FDA says it has already seized "thousands of units" of the counterfeit semaglutide, some of which was being sold through legitimate sources.
"Some counterfeit products may still be available for purchase," the FDA said in a statement last week.
The FDA said that it was working with Novo Nordisk to test the seized counterfeit drugs but has yet to come to a conclusion about the nature of the drugs and their safety.
The fake Ozempic is labeled with a lot number NAR0074 and serial number 430834149057; anyone with this product should cease distribution or use.
In addition to the counterfeit drugs, the FDA said an analysis from collected samples found the included needles are counterfeit as well.
"Accordingly, the sterility of the needles cannot be confirmed, which presents an increased risk of infection for patients who use the counterfeit products," the agency said.
Federal regulators did not mention how the phony Ozempic made its way into the drug market, but said they are continuing to investigate the issue.
The FDA said it is aware of five adverse events from the affected lot, none of which are serious and are consistent with known common adverse reactions to authentic Ozempic -- which are nausea, vomiting, diarrhea, abdominal pain and constipation.
"FDA's investigation is ongoing, and the agency is working with Novo Nordisk to identify, investigate, and remove further suspected counterfeit semaglutide injectable products found in the US," the agency said.
Ozempic suppresses appetite and prolongs fullness by mimicking the role of a natural hormone, called GLP-1. The drug was intended for people with diabetes to help manage blood sugar, but the medication has taken on a life on its own due to rapid weight-loss results.