If you experience chest pain, dizziness, or nausea during sexual activity, call your doctor immediately and avoid sexual activity until your doctor tells you otherwise. Sildenafil belongs to a group of medicines called phosphodiesterase 5 PDE5 inhibitors. You may opt-out of email communications at any time by clicking on the unsubscribe link in the e-mail. This medicine is available only with your doctor’s prescription. Shake the liquid well for 10 seconds before each use to mix the medication evenly. · US Brand Name Revatio Viagra Descriptions Sildenafil is used to treat men who have erectile dysfunction (also called sexual impotence). Sildenafil belongs to a . Generic: Sildenafil. Form: oral tablet; Strengths: 25 mg, 50 mg, mg; Brand: Viagra. Form: oral tablet; Strengths: 25 mg, 50 mg, mg; Adult dosage (ages . Sildenafil (Liqrev, Revatio) is used to improve the ability to exercise in adults (Liqrev, Revatio) and children 1 year of age and older (Revatio) with pulmonary arterial .