An FDA-approved safe drug for men's health is called Cenforce D. It is mostly composed of sildenafil citrate and is classified as a PDE 5 inhibitor, which means that it keeps an erection going for a long period during physical activity even when there is blood flow to the penis. During sexual activity, this movement helps men maintain firm, long-lasting erections. For best effects, take this pill half an hour before engaging in any sexual activity.