Children 1 year of age and older weighing 45 kilograms kg or more—20 mg 3 times a day. This can range from government-sponsored programs to manufacturer coupons. The business model is the exact same, and the prices between PrimeRx and GoodRx are similar too. Follow the manufacturer’s directions to use and clean the oral syringe. How and when to take sildenafil It’s important to take sildenafil as advised by a doctor or pharmacist. What special precautions should I follow? Walgreens, for instance, has a prescription drugs discount card.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. Sildenafil citrate is a white to off-white crystalline powder with a solubility of mg/mL in water and a molecular weight of VIAGRA is formulated as blue, film-coated rounded-diamond-shaped tablets equivalent to 25 mg, 50 mg, and mg of sildenafil for oral administration. Viagra (sildenafil) as low as. $ View other PDE5 Inhibitors. Sildenafil (Viagra, Revatio) is a moderately priced drug used to treat erection problems in men. It is also used to treat pulmonary arterial hypertension, a serious heart and lung condition. This drug is more popular than comparable drugs. It is available in generic and brand versions.