The US Food and Drug Administration sent out a warning last Tuesday about counterfeit versions of the drug Adderall — in a 30-milligram dose — that are available for purchase online. Adderall, used to treat attention deficit hyperactivity disorder (ADHD) and narcolepsy, is classified as a controlled substance and has been in short supply for months.

According to the FDA, the counterfeit version being sold on the Internet contains the wrong active ingredients.

Counterfeit Adderall tablets, which are white, look strikingly different from the real version, which is orange/peach in color and manufactured by Teva Pharmaceuticals. Real Adderall, in a 30-milligram dose, is imprinted with a “dp” on one side and “30” on the other side of the tablet.

The agency added that the Adderall 30-milligram product may be counterfeit if:

■ The product comes in a blister package.

■ There are misspellings on the package such as “NDS” instead of “NDC”; “Aspartrte” instead of “Aspartate”; Singel” instead of “Single.”

■ The tablets have no markings on them.

Consumers who suspect they’ve purchased the fraudulent Adderall should file a report online at the FDA’s MedWatch site or call 800-332-1088 to request a reporting form.