Complex Regional Pain Syndrome



Complex Regional Pain Syndrome

Complex regional pain syndrome (CRPS) is a poorly understood condition in which a person experiences persistent severe and debilitating pain.

Although most cases of CRPS are triggered by an injury, the resulting pain is much more severe and long-lasting than normal.

The pain is usually confined to one limb, but it can sometimes spread to other parts of the body.

The skin of the affected body part can become so sensitive that just a slight touch, bump or even a change in temperature can provoke intense pain.

Affected areas can also become swollen, stiff or undergo fluctuating changes in colour or temperature.

Many cases of CRPS gradually improve to some degree over time, or get completely better. However, some cases of CRPS never go away, and the affected person will experience pain for many years.

Read more about the symptoms of CRPS.

When to seek medical advice

You should see your GP if you have persistent pain that's preventing you from carrying out everyday activities.

CRPS can be difficult to diagnose because it involves a number of tests to rule out other possible causes. It's best to seek help as soon as possible, because early treatment may reduce unnecessary suffering.

Read more about diagnosing CRPS.

Causes of CRPS

The cause of CRPS is unknown, but it's generally thought to be the result of the body reacting abnormally to an injury.

It used to be thought that CRPS was a psychosomatic condition (the symptoms were "all in the mind") but research has disproved this.

Read more about the possible causes of CRPS.

Who is affected?

It's difficult to estimate exactly how common CRPS is, as many cases may go undiagnosed or misdiagnosed. A study claimed that up to 1 in 3,800 people in the UK develop CRPS each year.

CRPS can begin at any age, including in children, although the average age for symptoms to start is around 50. Women make up around 3 out of 4 cases.

Treating CRPS

Treatment for CRPS involves four main aspects:

  • education and self-management being given clear information about your condition and advice on any steps you can take to help manage your condition yourself
  • physical rehabilitation - treatment to help manage your symptoms and reduce the risk of long-term physical problems, such as physiotherapy exercises
  • pain relief - treatments to help reduce your pain, such as anticonvulsants or antidepressants
  • psychological support - interventions to help you cope with the emotional impact of living with CRPS, such as cognitive behavioural therapy (CBT)

Due to the complex nature of CRPS, a number of different professionals will usually be involved in your care.

Read more about treating CRPS.

Chronic usually means a condition that continues for a long time or keeps coming back.
Nervous system
The brain, spinal cord and nerves.
Neuropathic pain
Neuropathic pain is caused by problems with the body's nerves, either because the nervous system is not working properly or because the nerves themselves have been damaged.
Remission is when the symptoms of a condition are reduced (partial remission) or go away completely (complete remission).



The main symptom of complex regional pain syndrome (CRPS) is pain, which can sometimes be severe, continuous and debilitating. It's usually confined to one limb, but can spread to other parts of the body in some cases.

Chronic pain

The pain associated with CRPS is usually triggered by an injury, but is a lot more severe and long-lasting than would normally be expected.

The pain may be a mix of burning, stabbing or stinging sensations, but there may also be a tingling sensation and numbness.

You may have periods of pain lasting a few days or weeks, called flare-ups, where the pain gets worse. Stress in particular can lead to flare-ups, which is why relaxation techniques and mindfulness training can be an important part of treating CRPS.

If you have CRPS, your skin in the affected area can become very sensitive. Even the slightest touch, bump or change in temperature can provoke intense pain.

You may hear this described in the following medical terms:

  • hyperalgesia - feeling pain from pressure or temperature that wouldn't normally be painful
  • allodynia - experiencing pain from a very light stroke of the affected skin

Other symptoms

In addition to chronic pain, CRPS can also cause a range of other symptoms, including:

  • strange sensations in the affected limb - it may feel as if the affected limb doesn't belong to the rest of your body, or it may feel bigger or smaller than the opposite, unaffected limb
  • alternating changes to your skin sometimes your skin in the affected limb may be hot, red and dry, whereas other times it may be cold, blue and sweaty
  • hair and nail changes - your hair and nails in the affected limb may grow unusually slowly or quickly and your nails may become brittle or grooved
  • joint stiffness and swelling in the affected limb (oedema)
  • tremors and muscle spasms (dystonia)
  • difficulty moving the affected body part
  • difficulty sleeping (insomnia)
  • small patches of fragile bones (osteoporosis) in the affected limb although there's no evidence this could lead to fractures

In very rare cases, CRPS can also lead to further physical complications, such as skin infections and ulcers (open sores), muscle atrophy (where the muscles begin to waste away) and muscle contractures (where the muscles shorten and lose their normal range of movement). 

Some of these problems can make it very difficult for people with CRPS to move around.

Psychology in CRPS

The emotional strain of living with chronic pain can sometimes lead to psychological problems, such as depression and anxiety. During periods of extreme pain, some people may even consider suicide.

See your GP as soon as possible if you've been experiencing feelings of depression or suicide. They'll be able to provide help and support.

Alternatively, you can call the Samaritans on 116 123 or email They're available 24 hours a day to talk through any issues you may be experiencing, and will do so in total confidence.

When to see your GP

You should see your GP if you have persistent pain that's preventing you from carrying out everyday activities.

CRPS can be difficult to diagnose, and it's best to seek help as soon as possible, because early help can reduce unnecessary suffering.

Read more about diagnosing CRPS.

Blood vessels
Blood vessels are the tubes in which blood travels to and from parts of the body. The three main types of blood vessels are veins, arteries and capillaries.
Joints are the connection point between two bones that allow movement.



Although complex regional pain syndrome (CRPS) has been a recognised medical condition for more than 150 years, its exact cause is still unclear.

Previous injury

The condition usually seems to develop within a month of an injury, either minor or more serious. These can include:

Most people recover from these injuries without experiencing any significant long-term effects, but people with CRPS develop pain that's much more severe and long-lasting than usual.

The pain can spread beyond the site of the original injury, usually affecting an entire limb. For example, CRPS may affect your whole arm after an injury to your finger or hand. In some cases, more than one area of the body can be affected.

CRPS has also been known to occur after surgery to a limb or after part of a limb has been immobilised (for example, in a plaster cast).

CRPS after an injury

It's not known why some people develop CRPS after an injury. Due to the complex nature of the symptoms, it's unlikely the condition has a single, simple cause.

Some people even believe CRPS shouldn't be regarded as a single medical condition, because the symptoms could be the result of several different ones.

One of the main theories suggests that CRPS is the result of a widespread abnormal response to an injury that causes several of the body's systems to malfunction, including:

  • the central nervous system - the brain and spinal cord
  • the peripheral nervous system - the nerves that lie outside the central nervous system
  • the immune system - the body's natural defence against illness and infection
  • the blood vessels - the series of arteries and veins that transport blood around the body

These systems are responsible for many body functions often affected in people with CRPS, such as:

  • detecting pain and transmitting pain signals
  • triggering inflammation (swelling)
  • controlling temperature and movement

It's also been suggested that some people may be more susceptible to CRPS because of genetic factors. However this isn't clear and it's very unlikely other members of your family will be affected if you have CRPS.

In the past, some people believed CRPS may be a psychological condition that makes people think they are experiencing pain. However, this theory has been largely disproven.

Blood vessels
Blood vessels are the tubes in which blood travels to and from parts of the body. The three main types of blood vessels are veins, arteries and capillaries.
Free radicals
Oxygen free radicals are a toxic waste product that is produced as a natural by-product of cell activity.
Genetic is a term that refers to genes. Genes are the characteristics inherited from a family member.
Hormones are groups of powerful chemicals that are produced by the body and have a wide range of effects.
Immune system
The immune system is the body's defence system, which helps protect it from disease, bacteria and viruses.
Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.
Nervous system
The brain, spinal cord and nerves.
Periphery nerves
The periphery nerves are a network of nerves that run from the brain and spinal cord and carry impulses to and from the rest of the body, such as the limbs and organs. They are responsible for the body's senses and movements.



There's no single test for complex regional pain syndrome (CRPS). It's usually diagnosed by ruling out other conditions that have similar symptoms.

Some of the tests you may have to rule out other conditions can include:

A physical examination may also be carried out by your GP or another specialist to check for physical signs of CRPS, such as swelling and changes to your skin's temperature and appearance. Any physical exam should be gentle so it doesn't increase your pain.

A diagnosis of CRPS can usually be made if you have clear symptoms of the condition and no other possible cause can be found.


If you're diagnosed with CRPS, or if the diagnosis is uncertain, you'll usually be referred to a local specialist pain clinic. These are mostly located within hospitals.

Referrals are ideally made as soon as possible to ensure treatment can be started quickly, because treatment may reduce unnecessary suffering.

Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.
Joints are the connection point between two bones that allow movement.
Damage to the body's tissues.



There's no known cure for complex regional pain syndrome (CRPS), but a combination of physical treatments, medication and psychological support can help manage the symptoms.

It's estimated that around 85% of people with CRPS slowly experience a substantial reduction in their pain and some of their symptoms over the first two years after the condition starts.

However, some people experience continuous pain despite treatment. In rare cases, further problems may develop, such as muscle wastage in the affected limb.

There's currently no way to predict who will improve and when this may happen.

Your treatment plan

Treatment for CRPS involves four main areas:

  • education and self-management advice about any steps you can take to help manage the condition
  • physical rehabilitation - to help improve your function and reduce the risk of long-term physical problems
  • pain relief - treatments to help reduce your pain
  • psychological support - interventions to help you cope with the emotional impact of living with CRPS

Some of the main treatments used are described below.


As part of your treatment, you will be advised about things you can do yourself to help control your condition.

This may include:

  • education - to help you understand your condition
  • support to stay active and use the affected body part
  • learning techniques to help you manage increases in pain 
  • learning relaxation methods to help improve your quality of life 
  • advice regarding activity management - to help avoid peaks and dips in activity despite pain
  • continuing rehabilitation treatments at home, such as desensitisation techniques (see below)
  • accessing any support groups in your local area

Read more advice about living with pain.

Physical rehabilitation

Physical rehabilitation involves a number of different treatments.

The aim of these treatments is to gradually allow people to increase their activities and function without making the pain worse. This can be difficult as any movements or stimulation of the limb will increase pain or the other symptoms of CRPS such as swelling, colour changes and sweating.

If exercise or therapy is pushed too hard this can aggravate the condition so it's important for your therapy to be delivered or supported by a therapist with experience of CRPS.

Some of the techniques that may be used as part of your physical rehabilitation programme are described below.


Your exercise plan may include a range of gentle exercises, from simple stretches to exercises in water (hydrotherapy) or weight-bearing exercises.


Desensitisation is a technique used to reduce the sensitivity of body parts affected by CRPS.

It usually involves touching an unaffected body part, close to the affected body part, with materials of different textures, such as wool and silk, and concentrating on how this feels. The same materials are then gradually applied to the painful, affected body part while trying to recall what it felt like when you were touching the unaffected body part.

This process is likely to be uncomfortable or painful at first, but it may eventually reduce the sensitivity in the affected body part so it's more similar to unaffected areas.

Mirror visual feedback and graded motor imagery

Performing movement can often be difficult, as information which the brain needs to perform movements is often missing or confused.

Several techniques, such as mirror visual feedback and graded motor imagery, aim to improve movements by retraining the brain in respect to these missing or confused bits of information.

Pain relief

There are several medicines that may help to treat CRPS, which your pain specialist will be able to discuss with you.

Your treatment team will try lower-strength painkillers first, and will only use stronger painkillers if necessary.

None of the medicines used to treat people with CRPS are licensed for this use in the UK. This means these medicines may not have undergone clinical trials to see if they're effective and safe in treating CRPS specifically.

However, these medications will have a licence to treat another condition and will have undergone clinical trials for this. Doctors may choose to use an unlicensed medication if they're thought to be effective and the benefits of treatment outweigh any risks.

Some of the main pain relief treatments are discussed below.

Non-steroidal anti-inflammatory drugs (NSAIDs)

The first painkillers often used to treat CRPS are over-the-counter painkillers called non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen.

These medications can help reduce the pain caused by the injury that triggered CRPS. They can also treat CRPS-associated pains, such as muscle pain in the shoulder when the CRPS is in the hand. However, NSAIDs are unlikely to directly reduce CRPS pain. 


Anticonvulsants are usually used to treat epilepsy, but have also been found to be useful for treating nerve pain. Gabapentin and pregabalin are the most widely used anticonvulsants for treating CRPS.

Common side effects of these medications include drowsiness, dizziness and weight gain. There's a small increased risk of suicidal thoughts, which may be seen as early as a week after starting treatment.

You should avoid suddenly stopping treatment with these medications, because you may experience withdrawal symptoms. If you feel you no longer need to take it, your GP will arrange for your dose to be slowly reduced over a period of at least a week.

Tricyclic antidepressants

Tricyclic antidepressants (TCAs) were originally designed to treat depression, but like anticonvulsants were found to be effective in treating nerve pain. Amitriptyline and nortriptyline are the most widely used TCAs for treating CRPS, although nortriptyline generally has fewer side effects.

These medications can often improve sleep, and are generally taken in the early evening, to reduce the risk of "hangover" effects the next morning.

Possible side effects include:

  • dry mouth
  • blurred vision
  • constipation
  • heart palpitations
  • difficulty urinating

You may experience withdrawal effects if you stop taking these medications suddenly. If you feel you no longer need to take TCAs, your GP will arrange for your dose to be slowly reduced over a period of at least four weeks.


If you're experiencing severe pain, opioids such as codeine and morphine can sometimes provide pain relief.

Common side effects of opiate painkillers include:

  • nausea and vomiting
  • constipation
  • dry mouth
  • tiredness
  • cognitive problems (thinking processes can be slower)

Long-term use of high doses has been linked to more serious problems, such as depression, absent periods in women, and erectile dysfunction in men.

The benefits of using opioids may sometimes outweigh the risks, but unfortunately these medications are often not very effective in CRPS. Long-term use of high doses is generally not recommended, although exceptions may be made in a small number of cases under the care of a pain specialist.

Although addiction is rare, there's a risk you may become dependent on opioids. This means your body and mind don't want to stop taking them, even if they're not very effective. You may feel worse for a limited period of time when you do reduce or stop taking them.

Spinal cord stimulation

If medication doesn't lessen your pain, a treatment called spinal cord stimulation may be recommended.

This involves having a device placed under the skin of your tummy or buttocks, attached to a lead placed close to your nerves in the spine. This device produces mild electrical pulses that are sent to your spinal cord.

These pulses change how you feel pain. You may feel a tingling sensation in the part of your body that usually hurts, which masks the pain. The level of stimulation can be adjusted as your pain improves or gets worse, and the device can be removed if necessary.

The National Institute for Health and Care Excellence (NICE) states that spinal cord stimulation should only be considered if:

  • you're still experiencing pain after six months of trying other treatments
  • you've had a successful trial of the stimulation - the trial only involves placing the leads, not implanting them

Your care team will discuss spinal cord stimulation with you if they think it could help.

Psychological support

Living with a long-term, painful condition can be distressing, and people with CRPS may experience psychological problems, such as anxiety and depression.

It's important to look after your psychological wellbeing, because feelings of depression and anxiety can interfere with your rehabilitation.

Psychological therapies can also be useful in helping you cope better with the symptoms of pain. For example, some studies have shown that cognitive behavioural therapy (CBT) can help in the management of long-term pain.

These therapies are often taught to small groups of patients with severe pain, together with rehabilitation techniques, in programmes called "pain management programmes" (see below).

The aim of CBT is to help you understand how your problems, thoughts, feelings and behaviour can affect each other. By discussing and altering how you feel about your condition, CBT can help you cope with your symptoms and make it easier for you to continue with your rehabilitation programme.

The abdomen is the part of the body between the chest and the hips.
Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.
Joints are the connection point between two bones that allow movement.
Spinal cord
The spinal cord is a column of nervous tissue located in the spinal column. It sends messages between the brain and the rest of the body.