Priapism symptoms vary depending on the type of priapism. The two main types of priapism are ischemic and nonischemic priapism.

Ischemic priapism

Ischemic priapism, 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:

• Erection lasting more than four hours or unrelated to sexual interest or stimulation
• Rigid penile shaft, but the tip of penis (glans) is soft
• Progressive penile pain

Recurrent or stuttering priapism, a form of ischemic priapism, is an uncommon condition. It's more common in males who have an inherited disorder characterized by abnormally shaped red blood cells (sickle cell anemia). Sickle cells can block the blood vessels in the penis. Recurrent priapism describes repetitive episodes of prolonged erections and often includes episodes of ischemic priapism. In some cases, the condition starts off with unwanted and painful erections of short duration and might progress over time to more frequent and more prolonged erections.

Nonischemic priapism

Nonischemic priapism, also known as high-flow priapism, occurs when penile blood flow isn't regulated appropriately. Nonischemic priapism is usually less painful than ischemic priapism. Signs and symptoms include:

• Erection lasting more than four hours or unrelated to sexual interest or stimulation
• Erect but not fully rigid penile shaft

An erection normally occurs in response to physical or psychological stimulation. This stimulation causes certain smooth muscles to relax, 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, smooth muscles or nerves — changes normal blood flow, and an erection persists. The underlying cause of priapism often can't be determined, but several conditions may play a role.

Blood disorders

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

• Sickle cell anemia
• Leukemia
• Other hematologic dyscrasias, such as thalassemia, multiple myeloma and others

The most common associated diagnosis in children is sickle cell anemia.

Alcohol and drug use

Alcohol, marijuana, cocaine and other illicit drug abuse can cause priapism, particularly ischemic priapism.

Injury

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

Other factors

Other causes of priapism include:

• A spider bite, scorpion sting or other toxic infections
• Metabolic disorders including gout or amyloidosis
• Neurogenic disorders, such as a spinal cord injury or syphilis
• Cancers involving the penis

Ischemic priapism can cause serious complications. The blood trapped in the penis is deprived of oxygen. When an erection lasts for too long, this oxygen-poor blood can begin to damage or destroy tissues in the penis. As a result, untreated priapism can cause erectile dysfunction.