More serious side effects may include a drop in blood pressure or an erection that lasts longer than four hours. The information provided is for educational purposes only and is not intended to replace discussions with a healthcare provider. Viagra is also informally known as “vitamin V”, “the blue pill”, or “blue diamond”, as well as various other nicknames. If you have an erection that lasts more than 4 hours, get medical help right away. Never purchase ED medications from a site or service that doesn’t require a prescription and medical documentation. Cialis tadalafil : This ED medication works with the same principle as Viagra, but lasts up to 36 hours. These PDE5 inhibitors may cause headache, flushing, drop in blood pressure, or other adverse effects.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. The cost for sildenafil . Price without insurance: starts at $6 per dose for 10 doses. Doses: 20, 25, 50, and mg. Supply: 30, 90, or days. Sildenafil is the generic form of Viagra and Revatio. It’s chemically. The price of Pfizer’s Viagra has doubledsince it was launched, according to a list of wholesale acquisition costs paid by pharmacies, obtained by BNET. In May .