Cenforce is a brand name for a range of medications that contain sildenafil citrate as their active ingredient. Sildenafil is commonly used to treat erectile dysfunction (ED) in men. Cenforce is typically taken about 30 minutes to an hour before anticipated sexual activity. It has a relatively rapid onset of action, with effects usually starting within 30 minutes. The duration of action is approximately 4 to 6 hours, during which time a man should find it easier to achieve and maintain an erection when sexually stimulated.