What should I do if I forget a dose? Its effects often last for 4 to 5 hours. History Sildenafil compound UK, was synthesized by a group of pharmaceutical chemists led by Simon Campbell [55] working at Pfizer’s Sandwich, Kent , research facility in England. Before taking sildenafil, tell your doctor and pharmacist if you are allergic to sildenafil, any other medications, or any of the ingredients in sildenafil tablet or suspension. It works for up to 36 hours. Oral ED medicines might not work or might be dangerous if you also take any of the following: Nitrate medicines. What special dietary instructions should I follow?Viagra (sildenafil) is approved to treat sexual dysfunction in men by the U.S. Food and Drug Administration (FDA), but it is sometimes prescribed to women off-label, which . Sildenafil oral tablet is used to treat erectile dysfunction (ED). It’s also used to treat pulmonary arterial hypertension (PAH). What is sildenafil? Sildenafil is a prescription . Sildenafil under the name Viagra is used to treat erectile dysfunction (impotence) in men. Another brand of sildenafil is Revatio, which is used to treat pulmonary arterial .