A common sexual complaint among men is the inability to orgasm, according to Irwin Goldstein, MD, director of San Diego Sexual Medicine and the editor in chief of the Journal of Sexual Medicine. There's a wide range of possible explanations, however, and doctors are generally able to pinpoint your problem through biological and psychological tests.

Hypothyroidism: The thyroid gland does not produce enough hormone.

Hypogonadism: Testicles do not produce enough testosterone.

Psychological causes: These may include depression, anxiety, or a panic disorder of some kind. (Difficulty achieving orgasm can also be a side effect of some antidepressant drugs, such as selective serotonin-reuptake inhibitors, or SSRIs.)

Neurological problems: Strokes, multiple sclerosis, and diabetic neurothapy can limit your ability to orgasm.

Physical injuries: Spinal cord injuries and other major wounds can have an effect.

Prostate problems: These include infections or surgery affecting the prostate or other pelvic organs.

These are some of the conditions that tests may turn up.

See your doctor or a sexual medicine specialist to find out the cause.