Cenforce 100 mg contains sildenafil citrate, which helps treat erectile dysfunction (ED) by improving blood flow to the penis. When sexually aroused, the body releases nitric oxide, which triggers an enzyme called cGMP to relax the smooth muscles in the blood vessels of the penis. Sildenafil works by blocking another enzyme, PDE5, which breaks down cGMP. By inhibiting PDE5, Cenforce allows cGMP to build up, causing the blood vessels to relax and widen, increasing blood flow. This enhanced circulation helps achieve and maintain an erection when stimulated. Cenforce only works with sexual arousal and does not cause automatic erections. It typically starts working within 30 to 60 minutes and lasts for 4 to 6 hours.