Viagra is not for use by females. As with sildenafil, a high-fat meal or alcohol keep the body from absorbing it as quickly. The trial results revealed that sildenafil had improved the patients’ depression, anxiety, and self-esteem. VIAGRA was evaluated primarily at doses of 25 mg, 50 mg and mg in 21 randomized, double-blind, placebo-controlled trials of up to 6 months in duration, using a variety of study designs fixed dose, titration, parallel, crossover. The recommended dosage for tablet and oral suspension formularies is 5 mg or 20 mg three times daily, 4 to 6 hours apart. Outline appropriate monitoring of sildenafil therapy in erectile dysfunction and pulmonary arterial hypertension.Drug Images What is Viagra? If you have erectile dysfunction (ED), your doctor may recommend that you take Viagra. It’s a prescription drug that’s used in adult males* . In most males,* Viagra works within 1 hour after it’s taken. It’s possible that Viagra can begin working within 30 minutes of being taken. But other times, it may take up to 4 hours to start. In the U.S. and most other countries, generic Viagra is only available with a prescription. However, many new telehealth services make it easier to get a prescription without making an in-person.