The U.S. Food and Drug Administration has issued a warning about counterfeit generic Adderall tablets being sold on the Internet. Adderall is approved by the FDA to treat attention-deficit hyperactivity disorder and narcolepsy.

The FDA says the product purports to be 30-milligram Adderall tablets, but it does not contain the right ingredients.

The bogus version was discovered "by a consumer, who noticed misspellings on on the fake product packaging," according to Denise Bradley, Teva Pharmacautical's vice president of corporate communications. Bradley said two incidents have been reported to the FDA, and Teva Pharmaceuticals continues to work with the FDA on the investigation.

The pills contain the pain drugs tramadol and acetaminophen instead. The agency says the counterfeit tablets are white and round, and they do not have any markings like letters or numbers. Genuine Adderall tablets are an orange/peach color and have the letters "dp" embossed on one side with the number 30 on the opposite side.

Adderall is made by Teva Pharmaceutical Industries Ltd., and it is used to treat ADHD and narcolepsy. The drug is in short supply because of shortages of the active ingredients.

The FDA website offers tips for consumers who want to purchase prescription drugs using the Internet. First, make sure that the site requires a prescription and has a pharmacist available to answer questions. Consumers should only buy prescription medications from licensed pharmacies located in the United States.The National Association of Boards of Pharmacy has information about legitimate U.S. online pharmacies, and provides information about licensing and certification for online pharmacies. Consumers should never provide personal data, such as credit card numbers, unless they are sure an online site is legitimate and will protect their information.