Of the 16 patients, seven had a vasectomy, one had an undescended right testicle, one had redundant prepuce, one had a scrotal cyst and one had hyperplasia of the prostate. Structurally vardenafil Levitra is similar to sildenafil, while tadalafil Cialis is very different. When VSS began 4 h postdose, the median duration was 5 min 0—45 for sildenafil compared with 0 min for placebo 0— It is faster-acting than other drugs in the class and has a relatively milder side effect profile. This is called priapism, a medical emergency for which you should seek immediate care.Find information on sildenafil and cost, how generic and brand-name prices compare, what financial assistance is available, and more. Vision changes. Muscle pain. But there are some differences. With Viagra, there is a higher risk of vision changes than with Cialis. Among people who take Viagra or sildenafil, 3% get blue vision that lasts a few hours. On the other hand, Cialis has a slightly higher risk of muscle pain than Viagra and vardenafil. As a result, many will turn to Viagra (sildenafil) as a quick, effective solution for their ED. Viagra can last for about four hours or more in some people and should be taken 30 minutes to an hour before sexual activity. This article will discuss Viagra’s ability to work quickly, its current safety concerns, alternative treatments, and more.