Kamagra works by increasing blood flow to the penis, helping men achieve and maintain an erection during sexual activity. Sildenafil Citrate, the active ingredient, inhibits the enzyme phosphodiesterase type 5 (PDE5), which regulates blood flow in the penis. By blocking PDE5, Kamagra enhances the effects of nitric oxide, a natural chemical the body produces to relax the muscles in the penis.