The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive. Do not use this medicine if you are also using a nitrate medicine, often used to treat angina or high blood pressure. The following information includes only the average doses of this medicine. Kidney disease, severe or Liver disease, severe—Use with caution. This medicine is available only with your doctor’s prescription. Do not keep outdated medicine or medicine no longer needed.Sildenafil Citrate Coupons, Prices, and Savings Card. Brand Names: Revatio, Viagra. Sildenafil is used to treat male sexual function problems (impotence or erectile . Sildenafil is used to treat erectile dysfunction (ED) and to reduce blood pressure in pulmonary arterial hypertension (PAH). It is taken when needed for ED and daily for PAH. A headache, stomach upsets, and flushing are the main side effects, and it should not be taken within 24 hours of a nitrate. 5. Tips. Brand: Viagra. Form: oral tablet; Strengths: 25 mg, 50 mg, mg; Adult dosage (ages 18–64 years) Typical dosage: 50 mg, taken as needed about 1 hour before sexual activity. It can be taken