You can take it in a small dose daily or in a larger dose as needed. Sildenafil may cause side effects. John’s wort. You need to be sexually excited for it to work. What alternatives can I use for erectile dysfunction? Sildenafil Liqrev, Revatio is used to improve the ability to exercise in adults Liqrev, Revatio and children 1 year of age and older Revatio with pulmonary arterial hypertension PAH; high blood pressure in the vessels carrying blood to the lungs, causing shortness of breath, dizziness, and tiredness. You can take sildenafil with or without food.Key facts. Sildenafil (Viagra) is a medicine used to treat erectile dysfunction (ED, also called impotence). Sildenafil works by helping to relax the blood vessels in the penis, allowing more blood to flow in and cause an erection. You should take sildenafil about an hour before planned sexual activity, so it has time to work. The average retail price of the most common prescription of sildenafil could cost a couple hundred dollars, but you might be able to get that same prescription for as little as $11 . Compare prices and print coupons for Viagra (Sildenafil) and other drugs at CVS, Walgreens, and other pharmacies. Prices start at $ Welcome! You’re in GoodRx Provider Mode. Pay undefined at CVS Pharmacy with a GoodRx discount. That’s 74% off the retail price of $ CVS Pharmacy. $1, retail. Save 74% $ chevron_right.