Male erectile dysfunction is treated with sildenafil (Viagra), also referred to as impotence or the inability to get or keep an erection. Pulmonary arterial hypertension (PAH) in adults and children (Relation) one year of age and older is treated with sildenafil. PAH is defined as excessive blood pressure in the capillaries supplying blood to the lungs, resulting in weariness, dizziness, and shortness of breath. Sildenafil is a member of the class of medications known as phosphodiesterase (PDE) inhibitors. Sildenafil improves blood flow to the penis during sexual stimulation, aiding in the treatment of erectile dysfunction. Fildena 100 vs viagra erection is the resultant increase in blood flow. Sildenafil relaxes the blood vessels in the lungs to facilitate blood flow.