Viagra 100mg Tablets 4'sSildenafil is used to treat erectile dysfunction (impotence; inability to get or keep an erection) in men by increasing blood flow to the penis during sexual stimulation. Sildenafil is used to improve the ability to exercise in adults and children 1 year of age and older with pulmonary arterial hypertension PAH( high blood pressure in the vessels carrying blood to the lungs, causing shortness of breath, dizziness, and tiredness). Sildenafil treats PAH