Tadacip belongs to a class of drugs known as phosphodiesterase-5 (PDE-5). . In men with erectile dysfunction, blood flow to the penis is not sufficient to produce an erection. The main ingredient in Tadacip is tadalafil, It relaxes smooth muscles, widens the blood vessels in the penis. And this results in the blood filling and lifting the cavernous bodies. Tadacip should not be used in men with cardiac disease, For whom sexual activity is unacceptable. There is no information about priapism when erectile dysfunction is treated by Tadacip, But it can occur in patients treated with other PDE5 inhibitors sildenafil. If your erection lasts 4 hours or more, you should seek immediate medical attention to prevent permanent damage to your penis. Tell your doctor if you have an abnormal penis, including a curved penis and congenital defects in the penis.