Early or premature ejaculation is a dysfunction that is the premature expulsion of semen during intercourse. It occurs when there has been minimal or when sexual stimulation has not been controlled sufficiently to maintain vaginal penetration for the desired time. It is relatively common, and the causes are usually psychological, rather than physical, such as stress, depression, lack of confidence with a sexual partner, nervousness, excessive excitement, etc. The physical causes may originate in a low amount of serotonin. In this case, drugs that regulate the production of this substance in the brain were used. But treatment usually involves psychological therapy.