Priapism: Prolonged erection

Priapism is a prolonged erection of the penis. The unwanted, persistent erection isn't caused by sexual stimulation or arousal, and priapism is usually painful.

Priapism is an uncommon condition that needs immediate medical attention. Prompt treatment for priapism is usually needed to prevent tissue damage that could result in the inability to get or maintain an erection (erectile dysfunction).

Priapism is most common between ages 5 and 10 in boys and ages 20 and 50 in men.

Symptoms Causes Complications Prevention

Priapism causes abnormally persistent erections not related to sexual stimulation. Priapism symptoms may vary depending on the type of priapism. There are two main types: ischemic and nonischemic priapism.

Ischemic priapism

Ischemic, also called low-flow, priapism is the result of blood not being able to leave the penis. It's the more common type of priapism. Signs and symptoms include:

  • Unwanted erection lasting more than four hours
  • Unwanted erection off and on for several hours (stuttering priapism)
  • Rigid penile shaft, but usually soft tip of penis (glans)
  • Usually painful or tender penis

Nonischemic priapism

Nonischemic, or high-flow, priapism occurs when too much blood flows into the penis. Nonischemic priapism is usually painless. Signs and symptoms include:

  • Unwanted erection lasting at least four hours
  • Erect but not rigid penile shaft

When to see a doctor

If you have an erection lasting longer than four hours, go to the emergency room. If you experience a painful, persistent erection that resolves on its own in less than four hours, see your doctor. You may need treatment to prevent further episodes.

An erection normally occurs in response to physical or psychological stimulation. This stimulation causes certain blood vessels to relax and expand, increasing blood flow to spongy tissues in the penis. Consequently, the blood-filled penis becomes erect. After stimulation ends, the blood flows out, and the penis returns to its nonrigid (flaccid) state.

Priapism occurs when some part of this system — the blood, blood vessels or nerves — changes normal blood flow. Subsequently, an unwanted erection persists. Factors that can contribute to priapism include the following.

Blood disorders

Blood-related diseases may contribute to priapism — usually ischemic priapism, when blood isn't being able to flow out of the penis. These disorders include:

  • Sickle cell anemia
  • Leukemia

Sickle cell anemia is the most common cause of priapism in boys. Sickle cell anemia is an inherited disorder characterized by abnormally shaped red blood cells. These abnormally shaped cells can block the flow of blood.

Prescription medications

Priapism, usually ischemic priapism, is a known side effect of a number of drugs. The following drugs can sometimes cause priapism:

  • Oral medications used to manage erectile dysfunction, such as sildenafil (Viagra), tadalafil (Cialis) and vardenafil (Levitra)
  • Drugs injected directly into the penis to treat erectile dysfunction, such as papaverine
  • Antidepressants, such as fluoxetine (Prozac) and bupropion (Wellbutrin)
  • Drugs used to treat psychotic disorders, such as risperidone (Risperdal) and olanzapine (Zyprexa)
  • Blood thinners, such as warfarin (Coumadin) and heparin

Alcohol and drug use

Misuse of prescription drugs, and alcohol and drug abuse can cause priapism, particularly ischemic priapism. Possible causes include:

  • Recreational use of erectile dysfunction drugs
  • Drinking too much alcohol
  • Use of illegal drugs such as marijuana or cocaine


A common cause of nonischemic priapism — a persistent erection caused by excessive blood flow into the penis — is trauma or injury to your genitals, pelvis or the perineum, the region between the base of the penis and the anus.

Other factors

Other causes of priapism include:

  • Spinal cord injury
  • Blood clots
  • Poisonous venom, such as venom from scorpions or black widow spiders

In some cases, doctors are unable to identify the specific cause for priapism.

Ischemic priapism can cause serious complications. The blood trapped in the penis is deprived of oxygen. When an erection lasts for longer than four hours, this oxygen-poor blood can begin to damage or destroy tissues in the penis. As a result, untreated priapism may cause:

  • Erectile dysfunction, the inability of the penis to become or stay erect with sexual arousal
  • Disfigurement of the penis

Depending on the probable cause of the priapism, steps to prevent recurrent priapism may include:

  • Treating the disease that may have caused priapism
  • Changing medications if a prescription medication was the probable cause
  • Avoiding triggers, such as alcohol or illegal drugs
  • Self-injection of phenylephrine to stop prolonged erections
  • Hormone-blocking medications — only for adult men
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