Causes (in order of prevalence)

Characteristics

Vascular disease

Gradual onset

Vascular risk factors: diabetes mellitus, hypertension, hyperlipidemia, tobacco use

Neurologic disease, eg, spinal cord injury, autonomic dysfunction, surgical procedures

Gradual onset

Neurologic risk factors: diabetes mellitus, history of pelvic injury, surgery, or irradiation, spinal injury or surgery, Parkinson’s disease, multiple sclerosis, or alcoholism

Loss of bulbocavernosus reflex

Medications, eg, anticholinergics, antihypertensives, cimetidine, antidepressants

Sudden onset

Lack of sleep-associated erections or lack of erections with masturbation

Temporal association with a new medication

Psychogenic, eg, relationship conflicts, performance anxiety, childhood sexual abuse, fear of sexually transmitted diseases, “widower’s syndrome”

Sudden onset

Sleep-associated erections or erections with masturbation are preserved

Hypogonadism

Gradual onset

Decreased libido more than erectile dysfunction

Small testes, gynecomastia

Low serum testosterone concentration

Endocrine, eg, hypothyroidism, hyperthyroidism, hyperprolactinemia

Rare, < 5% of cases of erectile dysfunction