Learn about sildenafil (Viagra) usage and dosing. Read the latest news and reviews about the drug as well as potential side effects and popular alternatives. But Viagra is sometimes considered the most effective ED treatment because it’s been used for many years and has a lot of research supporting its effectiveness. A comprehensive academic analysis of sildenafil citrate (Viagra): mechanism of action via the NO–cGMP–PDE5 pathway, pharmacokinetics (t½ ~4 hours, bioavailability ~41%), history of discovery, clinical efficacy data, and adverse effect profile. Viagra (sildenafil) is used to treat erectile dysfunction or impotence in men. Includes Viagra side effects, interactions and indications. Learn more about Viagra, including its uses, dosage, side effects, and how to get it. Get detailed information about Viagra including uses, side effects, alternatives, and more. Consumers should beware of websites selling Viagra or Cialis cheap or without a doctor's prescription, as these are fake pills that could be harmful. Viagra and Cialis are generally safe in most patients (with the exception of patients on nitrites); however, there are some things you should know in advance. Many ED drugs are available online. Some men prefer this option for discretion and convenience. VIAGRA is supplied as blue, film-coated, rounded-diamond-shaped tablets containing sildenafil citrate equivalent to 25 mg, 50 mg, or 100 mg of sildenafil. Tablets are debossed with PFIZER on one side and VGR25, VGR50 or VGR100 on the other to indicate the dosage strengths. Food has a big impact on the effectiveness of sildenafil. Take sildenafil with a glass of water on an empty stomach. Try the medication by yourself at first. This will allow you to test out how it affects you before testing it with your partner.