This boosts blood flow and helps you get an erection from sexual activity. Studies show that Tadalafil and Sildenafil are both effective in about sixty to eighty percent of men with ED — depending on the dosage. These medicines all work well for ED. Sildenafil Viagra is used to treat erectile dysfunction impotence; inability to get or keep an erection in men. Ask your healthcare professional how you should dispose of any medicine you do not use. Read and follow these instructions carefully before you start using sildenafil and each time you get a refill of your medicine. This can cause anxiety, which might make erectile dysfunction worse.Interactions. 1. How it works. Sildenafil may be used to treat erectile dysfunction (ED or impotence) in men (Viagra brand) or pulmonary arterial hypertension . 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 . 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* with ED. With ED, you .