Cenforce 100 contains sildenafil, which belongs to a group of medicines called PDE5 inhibitors. It works by blocking the PDE5 enzyme, helping maintain higher levels of cGMP, a chemical that relaxes the smooth muscles and allows more blood to flow into the penis during sexual stimulation. This increased blood flow can help produce and maintain an erection. Sildenafil does not increase sexual desire and generally does not cause an erection without sexual stimulation. The 100 mg strength is a high dose, so it should be used only as directed by a healthcare professional.