Sildenafil, the main ingredient in Cenforce, works by suppressing PDE-5 (phosphodiesterase type 5), an enzyme that inhibits erections.
An enzyme called PDE-5 breaks down cyclic guanosine monophosphate, which is necessary for erection. When cyclic guanosine monophosphate is degraded, an erection cannot occur, a condition known as ED (erectile dysfunction).