The most common side effects of VIAGRA: headache; flushing; upset stomach; abnormal vision, such as changes in color vision such as having a blue color tinge and blurred vision; stuffy or runny nose; back pain; muscle pain; nausea; dizziness; rash. If you are taking sildenafil for erectile dysfunction, you are unlikely to miss a dose since this medication is taken as needed, not on a regular dosing schedule. 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. Its effects often last for 4 to 5 hours. It lasts 4 to 5 hours, or longer if you have mild to moderate ED. Sildenafil does not prevent pregnancy or the spread of sexually transmitted diseases such as human immunodeficiency virus HIV. Sildenafil works on the PDE5 enzyme in the lungs to relax the blood vessels.Viagra is absorbed quickly into your body. It can start working within 30 minutes, but it may take a couple hours for some people. However, one study on Viagra found that about 70% of men achieved erections in 30 minutes, and more than 80% of men achieved erections within 45 minutes. For most men, the effects of Viagra will start within . If you are noticing a price discrepancy, please give us a call. We’d be happy to help! We can be reached at , Monday through Sunday from 6am to 9pm CT. We updated the GoodRx app. We do that quite often these days, because we know getting access to affordable prescriptions and care is super-important to you. According to price-comparison site , generic Revatio will cost you as little as $ per pill, depending on where you fill your prescription. That’s .