A phone or video consultation is sometimes required for legal purposes. If too much is used, the chance of side effects is increased. Sorry something went wrong with your subscription Please, try again in a couple of minutes Retry. The following nonprescription or herbal products may interact with sildenafil: cimetidine Tagamet HB , St. These PDE5 inhibitors may cause headache, flushing, drop in blood pressure, or other adverse effects. Cialis tadalafil : This ED medication works with the same principle as Viagra, but lasts up to 36 hours.There is also a generic version of Viagra available, under the name sildenafil, in 25mg, 50mg, and mg strengths. 3. Downsides If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include. Cart. Transfer your prescription for Sildenafil (Generic for Viagra, Oral Tablet) on Amazon Pharmacy. FREE SHIPPING for Prime members. Sildenafil Prices, Coupons and Patient Assistance Programs. Sildenafil is a member of the agents for pulmonary hypertension drug class and is commonly used for Erectile Dysfunction, Pulmonary Arterial Hypertension, and Sexual Dysfunction – SSRI Induced. Brand names for sildenafil include Viagra, Revatio, and Liqrev.