Thousands of Internet and overseas pharmacies sell prescription drugs at discount prices, but American officials and pharmaceutical companies are now warning consumers that they may not be getting what they paid for.

Every month, the United States Food and Drug Administration (FDA) gets dozens of reports of counterfeit drugs. They may look exactly like the medicines your doctor would prescribe, but they often contain little or no active ingredients, or could contain additional ingredients that could have serious side effects.

To protect yourself from counterfeit drugs, do this:

• Check the FDA Web site (www.fda.gov), which posts counterfeit drug alerts, along with other helpful information on prescription and over-the-counter drugs.
• Be careful when ordering from online pharmacies. Check with the National Association of Boards of Pharmacy (www.nabp.net) to make sure the Web site you're dealing with is a licensed pharmacy.
• Steer clear of sites that don't offer access to a registered pharmacist to answer questions, or sites that don't have a U.S. address and phone number to contact.
• Avoid buying from overseas pharmacies either online or while traveling. It's generally illegal to import prescription drugs from abroad, and there are fewer controls in place to ensure those drugs are safe-and not counterfeits.