Few men's penises are completely straight when they are erect. It is common for an erect penis to have a slight curve in it. The curve can be up or down, or to the left or right. A curve of up to 30° is considered normal, and medical treatment is usually not needed unless the angle of curvature is more than 45°. A curved penis does not usually cause a man any problems when he is having sex. However, if the curvature of a penis changes, this could be caused by an illness called Peyronie's disease (see below). An erection that pokes through clothing is sometimes called a "manbulge".