It should never be relied upon for specific medical advice. Sudden vision loss in one or both eyes can be a sign of a serious eye problem called non-arteritic anterior ischemic optic neuropathy NAION. Efficacy Results in Subpopulations in Controlled Clinical Studies A review of population subgroups demonstrated efficacy regardless of baseline severity, etiology, race and age. Read more on male sexual health on the Sexual Health Australia site. Viagra doesn’t work instantaneously.Viagra Increases Your Sex Drive. Another common myth about Viagra is that it can increase your sex drive and cause you to feel more motivated to have sex. Viagra is designed to improve your physical performance during sex — that is, your ability to get and maintain an erection. Sildenafil (Viagra) is used to treat erectile dysfunction (impotence; inability to get or keep an erection) in men. 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 hypertension (PAH; high blood pressure in the vessels carrying blood to the . The dose of Cialis you need will depend on whether you’re taking it daily or as needed. Daily doses are often between and 5 milligrams (mg). The as-needed dose is usually 10 mg but can range from 5–20 mg. The typicaldose of Viagra is 50 mg. However, the dosage can range from 25– mg.