BigFun 100 Mg contains Sildenafil which belongs to a group of medicines called phosphodiesterase type 5 (PDE5) inhibitors. It is used to treat adult men with erectile dysfunction, also known as impotence. It happens when a man cannot get, or keep a hard, erect penis suitable for sexual activity. Erectile dysfunction (ED) is inability of men to attain and maintain an erect penis with sufficient rigidity to allow sexual intercourse. This medicine works by helping to relax the blood vessels in penis, allowing blood to flow into penis when you get sexually excited.