Never take 2 doses at the same time. If you are taking sildenafil for PAH, take the missed dose as soon as you remember it. Sildenafil comes as a tablet and suspension liquid to take by mouth. If you become pregnant while taking sildenafil, call your doctor. Never take an extra dose to make up for a forgotten one. You can take this medicine with or without food 30 minutes before sex, depending on the dose.Sildenafil (Viagra) is used to treat erectile dysfunction (impotence; inability to get or keep an erection) in men. 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 . AdYour meds, at a cost you’ll like. Visit GoodRx to find Rx coupons at a pharmacy near you. We’re here for you. GoodRx® has helped Americans save over $60B to date. Start saving now!5-Star Reviews · Over 70k Pharmacies · No Credit Card RequiredTypes: Sildenafil · Erection Problems · Erectile Dysfunction. 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.