Viagra (sildenafil) says "if u have an erection longer than 4 hrs." is it bad to have erection longer 4hrs if u haven't taken viagra (sildenafil)? as in hours of sex with gf

Four Hour Erection: It is very unusual for a male to have an erection that lasts for over four hours without ejaculation or periods of time when the erection is less firm. A four hour erection or more is called priapism and can be a very serious situation for a man where the tissues of the penis begin to lose oxygen and to die off. I doubt that sexual activity as you describe is the same thing.