Sildenafil comes as a tablet and suspension liquid to take by mouth. Talk to your doctor about eating grapefruit and drinking grapefruit juice while taking this medicine. Be sure to let your doctor and pharmacist know that you are taking these medications before you start taking sildenafil. If you feel nervous about how to talk to your doctor about ED, try using this checklist to help you find the right words. Sildenafil Viagra.Typical dosing for Sildenafil (Viagra) The typical dose is to take 50 mg of sildenafil (Viagra) by mouth, about 1 hour before sex, as needed. The maximum recommended dose is . How to get a prescription for Viagra; The dangers and prevalence of counterfeit Viagra; Lifestyle choices that can help improve your erections; Why you need a prescription for Viagra. Does Viagra require a prescription? Yes, and it’s because you’ll need to work . 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 .