The US Food and Drug Administration says medicines bought on several Canadian pharmacy websites have turned up as fakes.
The agency says it tested drugs intercepted on the way to US consumers and turned up counterfeits of 10 popular medications.
That list includes Lipitor, Crestor, Zetia, Diovan, Hyzaar, Actonel, Nexium, Celebrex, Arimidex and Propecia.
The seized drugs came from 10 online pharmacies.
Consumer officials say it's a case of buyer beware if you turn to the Internet for prescription drugs.