iErect, a new dietary supplement marketed as “100% natural” and sold over the Internet, was analyzed. It contains thiosildenafil, a sildenafil analogue already reported as an adulterant in herbal formulations, and a new compound whose structure was elucidated after isolation using NMR, MS and IR. It was named depiperazinothiosildenafil as it results from the hydrolytic cleavage of the S–N bond of the sulfonamide group of thiosildenafil. A capsule of iErect contains a very high amount (≈220mg) of thiosildenafil and ≈30mg of depiperazinothiosildenafil, which places consumers at risk for potentially serious side-effects.