If you are taking sildenafil to treat PAH, you will probably take sildenafil three times a day with or without food. Oral ED medicines might not work or might be dangerous if you also take any of the following: Nitrate medicines. Such patients must not apply any out-of-pocket expenses incurred using this Savings Offer toward any government insurance benefit out-of-pocket spending calculations, such as Medicare Part D true out-of-pocket TrOOP costs You are responsible for reporting use of this Savings Offer to any private insurer, health plan, or other third party who pays for or reimburses any part of the prescription filled using this Savings Offer, as may be required. Medicines that you take by mouth are called oral medicines. Severe liver disease. Your doctor or other health care professional can recommend one for you based on these factors, other health conditions you have and any other medicines you take. If you experience chest pain, dizziness, or nausea during sex, seek immediate medical help.FAQs What to consider Cost Overdose Ask your doctor Q&A Drug Images What is Viagra? If you have erectile dysfunction (ED), your doctor may recommend that you take Viagra. . Prices for Viagra can vary considerably among pharmacies. However, it can cost more than $ for 10 of the milligram (mg) tablets. Generic versions will generally cost less than the branded. The recommended dosage of Viagra for erectile dysfunction (ED) is 50 mg, taken as needed about 1 hour before sexual activity. You can take it 30 minutes to 4 hours before sexual activity. And you.