Avoid Big Penis supplements, the Food and Drug Administration again urged consumers this week.

The product promoted for sexual enhancement violates FDA regulations by containing a prescription drug without clearly disclosing it does, according to a public notification issued Wednesday.

Regulators previously advised consumers not to purchase or use Big Penis Male Sexual Stimulant three years ago. The FDA also identified the supplement while examining international mail shipments then.

The supplement contains sildenafil, the active ingredient in Viagra and other erectile dysfunction medications, according to the FDA. The drug can lower blood pressure to "dangerous levels" when taken with prescription drugs containing certain nitrates, including nitroglycerin, the FDA said in its notice.

Doctors and patients who experience side effects from the product can report the issues to the FDA's MedWatch Safety Information and Adverse Event Reporting Program.