Erection
Hormonal problems – diseases affecting the testicles or pituitary gland such as a tumor in the pituitary gland. (A tumor, also spelled tumour, is a bunch of cells growing out of control that can sometimes lead to cancer.) This can cause hypogonadism, which means that there are low levels of testosterone in the body. Testosterone is a hormone (chemical made by the body) that is important in libido (wanting to have sex).