The agency recommends doctors and purchasing administrators only buy drugs from wholesale distributors licensed in their states. Under a new federal law, all wholesalers must be state-licensed by the beginning of 2015.
Counterfeit or foreign versions of drugs often enter the U.S. from overseas.
The World Health Organization estimates that global sales of medicines that are fake, contaminated or otherwise illegal total $430 billion a year.
In developing countries, up to 50% of the drug supply may be fake. That's many times more than in developed countries, where most potentially dangerous fake drugs are sold through rogue Internet pharmacies.
But counterfeit drugs are increasingly getting into doctor's offices, pharmacies and hospitals.
In the U.S., for example, three times since 2012 counterfeit versions of the Roche Group cancer drug Avastin have infiltrated the wholesale supply and been sold to cancer clinics and hospitals. An unknown amount of those fakes was administered to patients.
Last year, a Montana man pleaded guilty to failing to report that the company he previously owned, Montana Healthcare Solutions, was importing and distributing fake vials of Avastin.