You need to be sexually excited for it to work. VIAGRA was evaluated primarily at doses of 25 mg, 50 mg and mg in 21 randomized, double-blind, placebo-controlled trials of up to 6 months in duration, using a variety of study designs fixed dose, titration, parallel, crossover. Sudden vision loss in one or both eyes can be a sign of a serious eye problem called non-arteritic anterior ischemic optic neuropathy NAION. Mutagenesis Sildenafil was negative in in vitro bacterial and Chinese hamster ovary cell assays to detect mutagenicity, and in vitro human lymphocytes and in vivo mouse micronucleus assays to detect clastogenicity. The pharmacokinetics of sildenafil are dose-proportional over the recommended dose range.VIAGRA may not be right for every man, but it has been shown to help approximately 4 out of 5 men get and keep erections hard enough for sex at doses of 50 mg or mg.* * Seventy-two percent, 80%, and 85% of the patients on 25 mg, 50 mg, and mg of VIAGRA, respectively, achieved erections hard enough for sex, compared to 50% on . The recommended dosage of Viagra for erectile dysfunction (ED) is 50 mg, taken as needed about 1 hour before sexual activity. You can take it 30 minutes to 4 hours before sexual activity. And you. The Savings Offer and Program expire on 12/31/ For further information, call , visit , or write: Viatris Inc., P.O. Box , Mission, KS Eligible patients may save on their VIAGRA® (sildenafil citrate) prescription with the VIAGRA savings card.