Proper Use Use sildenafil exactly as directed by your doctor. Do not take more or less of it or take it more often than prescribed by your doctor. Brand names Why is this medication prescribed? Remove the cap by pushing it down and twisting it counter-clockwise. Tell your doctor if any of these symptoms are severe or do not go away: headache. This medicine usually begins to work for erectile dysfunction within 30 minutes after taking it.Sildenafil tablets for erectile dysfunction come in different strengths ranging from 25mg to mg. The usual dose is 50mg, when you need it. Do not take it more than once a day. The dose can be increased to mg or decreased to 25mg depending on its effect. Take sildenafil up to 4 hours before you want to have sex. 1 day ago · Cost: If the price for branded Viagra is outside of your budget, Lemonaid’s $2 sildenafil pills are some of the lowest priced Viagra alternatives that we’ve found. Product details Usage: take. Financial assistance Next steps Viagra (sildenafil) is a brand-name oral tablet prescribed for erectile dysfunction. The cost of the drug with and without insurance can depend on .