drug is more popular than comparable drugs. Sildenafil is also sometimes used to treat pulmonary high blood pressure in the blood vessels that supply the lungs. It is also used to treat pulmonary arterial hypertension, a serious heart and lung condition. Erectile dysfunction is a condition where the penis does not harden and expand when a man is sexually excited, or when he cannot keep an erection, without physical action to the penis, such as that occurring during sexual intercourse, sildenafil will not work to cause an erection.