Kamagra 100 mg is a medicine commonly marketed for the treatment of erectile dysfunction (ED) in adult men. Its active ingredient is sildenafil citrate, the same active ingredient used in several approved ED medicines. Sildenafil belongs to a group of medicines called phosphodiesterase type 5 (PDE5) inhibitors. It works by increasing blood flow to the penis when a man is sexually stimulated, which can help produce and maintain an erection.