Priapism is a persistent and often painful erection that lasts for several hours.
The erection is not necessarily related to sexual stimulation or excitement, and does not subside after ejaculation (when semen is released from the penis).
The erection lasts longer than four hours. During this time, the shaft of the penis is rigid and inflexible, but the head of the penis (the glans) is usually soft. The penis is also usually painful or tender.
Priapism is a medical emergency – you should seek immediate medical assistance if you think you have it.
If it's not treated within 24 hours, your penis may be permanently damaged and you may have difficulties getting an erection in the future.
Types of priapism
There are three main types of priapism:
low blood flow (ischaemic) priapism – the most common and serious type of priapism usually caused by lack of blood flow through the penis
high blood flow (non-ischaemic) priapism – much rarer and usually caused by an injury to the genitals or perineum (the area in between the genitals and anus)
recurrent or intermittant (stuttering) priapism - similar to ischaemic priapism but characterised by recurrent, long-lasting, painful erections that ease after 2-3 hours.
What causes priapism?
Priapism happens when blood that fills the spongy tissue of the penis during an erection is unable to flow out of the penis.
Anything that affects the nervous system or blood flow (or both) can trigger priapism. It can occur, for example, as a complication of sickle cell anaemia (a genetic blood disorder), or as a rare side effect of several other medications, such as antipsychotic agents or anticoagulants.
If you have ischaemic (low blood flow) priapism, the sooner you receive treatment, the more effective it is likely to be.
Aspiration, a procedure that uses a needle and syringe to drain the blood out of your penis, is usually recommended.
If this does not work, medication may be injected into your penis which squeezes the blood vessels and helps push the blood out of your penis.
Surgery is only recommended if other treatments have failed. There are a number of different surgical procedures available, depending on the type of priapism you have.
Media last reviewed: 26/02/2015
Next review due: 26/02/2017
How common is priapism?
Priapism is rare in the general population, but fairly common in certain high-risk groups, such as males with sickle cell anaemia, and men taking medication for erectile dysfunction.
About one in four boys and nine in 10 men with sickle cell anaemia will experience at least one episode of priapism.
The risk of priapism as a side effect of treatment for erectile dysfunction is low and thought to be around one in 1,000.
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Causes of priapism
Priapism is caused by a problem with the blood supply to the penis. Certain medical conditions and medications can prevent blood leaving the penis.
When a man becomes sexually aroused, his nervous system releases a chemical called nitric oxide. Nitric oxide relaxes and widens the walls of the arteries that supply blood to the penis. This increases the blood flow to the spongy tissue of the penis, causing it to expand and harden into an erection.
After the feelings of sexual arousal have passed, the arteries in the penis should contract (become narrower), which pushes the excess blood out of the penis and returns it to its normal floppy state.
Anything that affects the nervous system or blood flow (or both) can trigger priapism.
Sickle cell anaemia
Sickle cell anaemia is an inherited blood condition where red blood cells develop abnormally. Red blood cells are usually round and flexible and carry oxygen from the lungs to the rest of your body.
However, in people with sickle cell anaemia, the shape and texture of red blood cells can change. They become hard, sticky and crescent-shaped.
In boys and men, it is possible for the hardened blood cells to clump together. This can lead to slow blood flow and clotting in the blood vessels of the penis, which can cause a painful and persistent erection.
A number of medications can sometimes disrupt the normal workings of the nerves that help trigger an erection by widening the arteries in the penis.
The nerves essentially ‘forget’ to narrow the arteries after the feelings of sexual arousal have passed, leading to ischaemic priapism.
Medication associated with ischaemic priapism includes:
medications for erectile dysfunction that are injected directly into the penis, such as alprostadil
blood-thinning medications, such as warfarin and heparin
some types of antidepressants, such as fluoxetine (Prozac), bupropion, and antipsychotic agents
some medications used to treat high blood pressure(hypertension), such as calcium channel blockers
In addition, some recreational drugs have also been linked to priapism, including:
methamphetamine (crystal meth)
Less common causes
Less common causes of priapism include:
thalassaemia – a blood condition similar to sickle cell anaemia
cancers of the blood, such as chronic leukaemia and multiple myeloma
cancers that have spread from nearby tissue or organs, such asprostate cancer or bladder cancer, and are disrupting the flow of blood inside the penis
spinal cord injury
Fabry disease – a rare, genetic condition that affects the metabolism (the process that converts food into energy)
Priapism can usually be diagnosed by your GP examining your penis and asking questions about your symptoms and medical history.
For example, you may be asked:
how long your penis has been erect
whether your penis is painful or tender
whether you have had previous episodes of priapism and how they were treated
whether you have a known blood disorder, such as sickle cell anaemia
whether you have recently taken recreational drugs, such as cocaine or ecstasy
You may also be asked whether you have recently injured your penis or perineum (the area in between your genitals and anus). This injury may occur up to two weeks before the development of the long-lasting erection.
Blood tests may be needed to find out what is causing your priapism. These can help detect underlying problems with your blood, such as anaemia (a lack of red blood cells), or unusually high numbers of white blood cells, which could be a sign of leukaemia.
Blood tests can also measure the levels of oxygen and carbon dioxide in your blood. Unusually low levels of oxygen and high levels of carbon dioxide would strongly suggest ischaemic priapism (low blood flow).
If non-ischaemic priapism is suspected due to an injury to your genitals or the surrounding area, you may be referred for a scan, such as anultrasound scan. This will help identify problems with the blood vessels in your penis.
Treatment for priapism will depend on the type of priapism you have.
High blood flow (non-ischaemic) priapism may not need treatment. A few cases get better on their own after a few hours.
If you have injured your genital area, and you have a painful and persistent erection, seek immediate medical assistance from your nearest accident and emergency (A&E) department. If it’s not treated within 24 hours you may have difficulties getting an erection in the future.
You may need surgery to temporarily prevent the flow of blood into your penis (see below).
If you are diagnosed with low blood flow (ischaemic) priapism, or have an episode of recurrent (stuttering) priapism, aspiration or sympathomimetic injections may be recommended.
The aim when treating recurrent priapism is to prevent further episodes.
Aspiration is the first treatment recommended for priapism.
Your penis is numbed with a local anaesthetic and a small needle and syringe is used to drain blood from your penis.
In some cases, the blood vessels may be ‘washed out’ with sterile water to get rid of any debris. This is known as irrigation.
Aspiration and irrigation usually help relieve painful symptoms and may result in your erection subsiding. However, you may need a number of treatment sessions before this happens.
If your symptoms do not respond to aspiration, the next step is to inject a type of medication known as a sympathomimetic directly into the tissue of your penis.
Sympathomimetics work by squeezing the blood vessels in your penis, helping them push blood out of your penis while also preventing more blood from being pumped in.
A type of sympathomimetic called phenylephrine is usually recommended because it has a lower risk of causing side effects compared with other sympathomimetics.
Side effects of phenylephrine include:
an increase in blood pressure, which can make you feel dizzy and lightheaded
rapid or irregular heartbeat
If you have a health condition that could be made worse by an increase in blood pressure, such as heart disease, you will need regular blood pressure checks and electrocardiograms (ECGs). An ECG measures your heart's electrical activity.
Surgery may be recommended if your symptoms fail to respond to aspiration or sympathomimetic injections. There are several surgical procedures available, depending on the type of priapism you have.
If you have ischaemic priapism, shunt surgery may be recommended. It involves creating a new route for blood to flow out of the penis.
This surgery is only effective if performed within a few hours of the development of the priapism, so it is important that you attend hospital quickly.
A small number of men who have surgery for priapism experienceerectile dysfunction afterwards. The risk is greater where the priapism has lasted a long time.
If you experience erectile dysfunction after surgery for priapism, you may need further surgery to treat it.
You should discuss the pros and cons of surgery for priapism with your surgeon beforehand.
If you have non-ischaemic (high blood flow) priapism, a surgical technique called embolisation may be used. It aims to stop the flow of blood into your penis by inserting a small device to block the damaged artery.
Medicines for recurrent (stuttering) priapism
The most commonly used medicines are:
gonadotrophin-releasing hormone (GnRH) agonists or antagonists
antiandrogens such as flutamide or bicalutamide
These medicines lower the levels of the hormone testosterone in your blood, which reduces the likelihood of getting an erection.
Hormonal treatments have potential side-effects so are only recommended for use in adult men. The use of other drugs to manage recurrent priapism is limited due to side-effects or lack of data regarding their safety.