Oklahoma City (CNN) -- The Food and Drug Administration has a warning for people who buy Adderall online -- it could be fake.
Several companies make Adderall and right now there is a shortage because of the lack of active ingredients and growing demand.
This FDA warning is about a counterfeit version of Teva Pharmaceuticals' 30 milligram Adderall.
The agency says the fake tablets are being sold with the wrong active ingredients.
The fake Teva pills have ingredients for acute pain ... not the amphetamines used to treat ADHD and narcolepsy.
So far, no warnings have been issued about internet fakes of the other brands.