Filagra is a medication used to treat erectile dysfunction (ED) in men. It contains Sildenafil Citrate as its active ingredient, which is a phosphodiesterase type 5 (PDE5) inhibitor. Sildenafil works by increasing blood flow to the penis during sexual stimulation, helping men achieve and maintain an erection. The recommended dose depends on the specific formulation (e.g., Filagra 50, Filagra 100). The usual approach is to take one tablet orally with a full glass of water, about 30 minutes to 1 hour before sexual activity. Sildenafil is most effective when there is sexual arousal. Duration of Action: Sildenafil generally has a duration of action of approximately 4-6 hours, providing a window of time during which sexual activity can occur.