Erectile dysfunction is a sexual disorder which occurs due to lack of blood flow. This disorder is found mostly in men. 40 men out of 100 have this disorder. Millions of men buy generic viagra online so that they can treat this disorder effectively. This disorder not only occurs due to lack of blood but also due to many of the physical or psychological factors. This disorder ruins the love life of people. Generic viagra contains sildenafil citrate as an active ingredient. This little blue pill works effectively to treat the erectile dysfunction disorder. This drug belongs to the group of PDE5 inhibitor and helps to have erection without any problem. This sildenafil directly works on the brain and makes the brain to send a message to the penis and penis release nitric oxide which is a chemical messenger. This nitric oxide helps to stimulate the cGMP enzymes. cGMP enzymes help to relax the blood vessel and make the blood to flow in the penile area. The lack of blood flow ha...