Penegra is a medication used to treat erectile dysfunction (ED) in men. It contains Sildenafil Citrate, which is the same active ingredient found in Viagra. Sildenafil works by increasing blood flow to the penis, helping men achieve and maintain an erection when sexually aroused. While Penegra can work for up to 6 hours, it's important to note that it won't cause a continuous erection for that period. It only facilitates the ability to get and maintain an erection during sexual arousal within that time frame. It doesn't cause spontaneous erections; it helps improve the response to sexual stimulation.