Cenforce 100 mg is a widely used medication for ED that contains sildenafil citrate as its active ingredient. Sildenafil works by inhibiting an enzyme called PDE5 (phosphodiesterase type 5), which is responsible for breaking down a molecule known as cyclic GMP (cGMP). During sexual arousal, cGMP is produced in the penile tissue, leading to the relaxation of smooth muscles and the dilation of blood vessels. By blocking PDE5, Cenforce 100 mg ensures that cGMP levels remain elevated, allowing for sustained blood flow and a firm erection. However, it's important to note that sexual stimulation is still required for the medication to be effective. Cenforce 100 mg typically takes about 30 to 60 minutes to start working, and its effects can last for up to four hours.