This is important for your overall health and safety, as certain medications can negatively interact with each other or cause existing conditions to worsen. Generic vs. Those with pre-existing conditions should always consult a healthcare provider before taking new medications or supplements. Kidney disease that needs to be treated with dialysis. The specific process for getting ED pills online depends on your chosen provider.Published on September 8, Viagra (sildenafil) is a common medication for erectile dysfunction (ED). Like any medication, how you take it may affect treatment outcomes. In this video, learn tips for taking Viagra to get the best results. Get sildenafil for as low as $, which is 95% off the average retail price of $ for the most common version, by using a GoodRx coupon. Prices Medicare Drug Info Side Effects Images Sildenafil (Viagra, Revatio) is a moderately priced drug used to treat erection problems in men. Sildenafil (Viagra). This medicine works best when you take it on an empty stomach an hour before sex. The body takes longer to absorb it after a high-fat meal or alcohol. Its effects often last for 4 to 5 hours. It might work longer if you have mild to moderate erectile dysfunction. Vardenafil.