It lasts 4 to 5 hours, or longer if you have mild to moderate ED. As with sildenafil, a high-fat meal or alcohol keep the body from absorbing it as quickly. This medication is taken with or without food an hour before sex. This medicine is available only with your doctor’s prescription. If you experience chest pain, dizziness, or nausea during sex, seek immediate medical help. Without physical action to the penis, such as that occurring during sexual intercourse, sildenafil will not work to cause an erection.While generic sildenafil and Viagra are equally safe and effective, the medications have one key. All you need to do is search for the brand or generic prescription drug using the boxes above and select your medication and checkout. Price Range / Box Strength; Viagra: Brand/Generic: $ – $ 25 – 5 – mg: View Product: Cialis: Brand/Generic. It is available in generic and brand versions. Generic sildenafil is covered by most Medicare and insurance plans, but some pharmacy coupons or cash prices may be lower. 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.