Read and follow these instructions carefully before you start using sildenafil and each time you get a refill of your medicine. If you’re not sure if you’re taking a nitrate, ask your doctor or pharmacist. Proper Use Use sildenafil exactly as directed by your doctor. Push the plunger of the syringe, then insert the tip into the bottle while holding the bottle upright on a flat surface. Prolonged erections can be dangerous. If you take too much sildenafil or take it together with these medicines, the chance for side effects will be higher.AdMany Americans pay far too much for their prescriptions. We’re here to help. GoodRx® finds the lowest prices at every pharmacy near you. See how much you can save!Service catalog: Prescription Coupons, Prescription Discounts, Online Doct. AdSay Goodbye to Performance Anxiety and Hello to Improved Sexual Stamina! Take Charge of Your Sexual Health with Our Top-Rated Male Enhancement Products! About sildenafil (Viagra) Sildenafil is a medicine used to treat erection problems (erectile dysfunction). Sildenafil is also sometimes used to treat pulmonary hypertension (high blood pressure in the blood vessels that supply the lungs). If you have erection problems sildenafil works by temporarily increasing blood flow to your penis when.