You’ll soon start receiving the latest Mayo Clinic health information you requested in your inbox. For erectile dysfunction, it’s best to take sildenafil on an empty stomach. Children 1 year of age and older weighing 20 to 45 kg—20 mg 3 times a day. Do not keep outdated medicine or medicine no longer needed. If you experience a prolonged or painful erection for 4 hours or more, contact your doctor immediately. Sildenafil Viagra. The trial results revealed that sildenafil had improved the patients’ depression, anxiety, and self-esteem.Yes. Walmart Pharmacy offers an easy prescription experience, from medication refills with just a few clicks to low-cost generic meds starting at just $4. You can also transfer your prescription online quickly and easily. Just click “start a transfer” to create an account. Walmart’s Specialty Pharmacy can also make it easy for you to get the. 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. For sildenafil to work properly, you’ll need to be sexually excited. Valid at all major chains including Walgreens, CVS Pharmacy, Target, WalMart Pharmacy, Duane Reade and 65, pharmacies nationwide. No manufacturer promotions could be .