Priapism is an abnormally prolonged and often painful erection. This erection may not be related to sexual desire or stimulation. It often won't be relieved by orgasm.
Priapism may start after prolonged sexual activity, although this by itself is not believed to cause priapism. Most men seek medical attention within hours to days, but a few people may have a partial erection that persists for weeks.
Priapism can affect males of any age. Most cases occur in boys aged 5 to 10 years or men aged 20 to 50 years. In young boys, the most common cause is sickle cell disease. In adult males, the leading cause is drug treatment of erectile dysfunction, especially injection therapy. Other less common causes include recreational drug use, trauma to the genitals or groin, other medications and spinal cord problems.
In up to one-third of cases, no specific cause can be found.
In a normal erection, the veins that drain blood from the penis narrow and cause blood to back up, which makes the penis stiffen and swell. After the veins relax and open, the penis will not be erect.
In most cases of priapism, these veins do not relax after orgasm, which causes the penis to remain erect. Less commonly, priapism occurs when so much blood flows into the penis that it cannot drain, even through veins that function properly. This increased blood flow is usually caused by a damaged blood vessel.