Premature ejaculation can be caused by temporary depression, stress or anxiety about a relationship, unrealistic expectations about performance or a history of sexual problems.
A number of biological factors could be the cause of premature ejaculation including abnormal hormone levels, abnormal reflex activity of the ejaculatory system, hyperthyroidism or inflammation or infection of the prostate or urethra.
It is believed that the neurotransmitter serotonin (5HT) plays a central role in controlling ejaculation. Low levels of serotonin in specific areas of the brain may cause premature ejaculation. Studies have shown that increases in serotonin levels can help delay ejaculation in some men.
Many physicians believe that penile hypersensitivity plays a predominant role in the ejaculatory response while others believe that premature ejaculation is the result of a combination of multiple contributing factors. The success of topical (applied to skin) medications provides strong reason to believe that penile sensitivity does contribute to premature ejaculation.