Vardenafil usually works for 4 to 5 hours. As with sildenafil, a high-fat meal or alcohol keep the body from absorbing it as quickly. The information provided is for educational purposes only and is not intended to replace discussions with a healthcare provider. ED medications can cause side effects, and it’s crucial to have access to a medical provider if needed. Rarely reported side effects include: an erection that will not go away priapism.Q&A Drug Images What is Viagra? If you have erectile dysfunction (ED), your doctor may recommend that you take Viagra. It’s a prescription drug that’s used in . According to price-comparison site test1.ru, generic Revatio will cost you as little as $ per pill, depending on where you fill your prescription. That’s . 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 .