The U. S. Food and Drug Administration (FDA) warned on Thursday that "Stiff Nights", a product marketed as a dietary supplement for sexual enhancement, contains an ingredient that can dangerously lower blood pressure and is illegal.

Following a consumer complaint, the FDA determined that the product contains sulfoaildenafil. This is a chemical similar to sildenafil, the active ingredient in Viagra. Sulfoaildenafil may interact with prescription drugs known as nitrates, including nitroglycerin, and cause dangerously low blood pressure.

"Because this product is labeled as an 'all natural dietary supplement', consumers may assume it is harmless and poses no health risk", said Deborah M. Autor, Director of FDA's Center for Drug Evaluation and Research Office of Compliance. "In fact, this product is illegally marketed and can cause serious complications".

Consumers and health care professionals should report adverse effects of such drugs to the FDA's MedWatch program at 800-FDA-1088 or online at fda. gov/medwatch/report. htm The FDA remains committed to stopping the illegal marketing of unapproved drugs and will continue to protect the public with vigorous law enforcement and criminal prosecution of violators.