The U.S. Food and Drug Administration ordered the immediate recall of True Man Sexual Energy Nutriment Capsules and Energy Max Energy Supplement Men's Formula Capsules, both made by America True Man Health Inc., of West Covina, Calif.

The products, advertised as "natural," have been labeled by the FDA as "illegal drug products that contain potentially harmful, undeclared ingredients." Specifically, the government drug regulator has found the company did not declare the active ingredients thione, an analog of sildenafil; or piperadino vardenafil, an analog of vardenafil. Both are substances which treat erectile dysfunction and are found in Viagra and Levitra, respectively.

"These products threaten the health of the people using them because they contain undeclared chemicals that are similar to the active ingredients used in FDA-approved prescription drug products," said Steven Galson, M.D., MPH, director of the FDA's Center for Drug Evaluation and Research. "The risk is even more serious because consumers may not know that these ingredients can interact with medications and dangerously lower their blood pressure."

The primary concern is that the two undeclared substances will interact with nitrates found in some prescription drugs such as nitroglycerin and may lower blood pressure to dangerous levels. At risk are especially men with diabetes, high blood pressure, high cholesterol or heart disease who often take drugs which contain nitrates.

Erectile dysfunction can be caused by a variety of factors. These include psychological factors; the consumption of alcohol and drugs; obesity; cigarette smoking; cavernosal disorders; hormonal disorders; spinal cord and brain injuries; and certain types of surgery.

The FDA said it could take legal action against the company if the products are not recalled. All customers who bought the product or otherwise have it in their possession should stop using it immediately and contact their health care provider if they have experienced any problems that may be related to taking this product, the U.S. Food and Drug Administration announced.