Premature ejaculation, the most common form of sexual dysfunction in men, often is due to nervousness over how well you'll perform during sex. But causes are often unclear.
In some cases, premature and inhibited ejaculation are caused by a lack of attraction for a partner, past traumatic events, and psychological factors, including a strict religious background that causes the person to view sex as sinful.
Certain drugs, including some antidepressants, may affect ejaculation, as can nerve damage to the spinal cord or back.