Figure 6. This can happen if you are sick with fever, diarrhea, or vomiting; sweat a lot; or do not drink enough liquids. People who use nitrates in any form or are being treated for pulmonary hypertension should not take sildenafil. Your primary care doctor should always know what medications you’re taking, including ED pills prescribed by another provider. Efficacy Results in Subpopulations in Controlled Clinical Studies A review of population subgroups demonstrated efficacy regardless of baseline severity, etiology, race and age.Sildenafil is a medicine used to treat erection problems (erectile dysfunction). Sildenafil is also sometimes used to treat pulmonary hypertension (high blood pressure in the blood vessels that supply the lungs). If you have erection problems sildenafil works by temporarily increasing blood flow to your penis when you get sexually excited. AdDon’t go to the pharmacy without checking prices at GoodRx® first. No commitment or fees. Find the lowest price in your neighborhood & use our free coupons to save up to 80%Service catalog: Prescription Coupons, Prescription Discounts, Online Doct. Takeaway Most Medicare plans do not cover erectile dysfunction (ED) medications like Viagra, but some Part D and Part C plans may help cover generic versions. Generic ED .