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 usually only affects 1 limb, but it can sometimes spread to other parts of the body.

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

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

CRPS often gradually improve over time. But some people with CRPS experience pain for many years.

When to get medical advice

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

Diagnosing CRPS can be difficult because it involves having tests to rule out other possible causes.

It's best to get help as soon as possible, as early treatment may help reduce your painful symptoms.

Causes of CRPS

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

It used to be thought that CRPS was a psychosomatic condition, where the symptoms are "all in the mind", but research has disproved this.

Who's affected?

It's difficult to estimate exactly how common CRPS is, as many cases may go undiagnosed or misdiagnosed. But it's thought to be fairly uncommon.

CRPS can affect people of any age, including in children. But it tends to be more common in women who are 60 to 70 years of age.

Treating CRPS

There's currently no cure for CRPS, but there are a number of treatments that can help manage the symptoms.

There are 4 main types of treatment:

  • education and self-management – being given clear information about your condition and advice on any steps you can take to help manage it 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 – treatments to help you cope with the emotional impact of living with CRPS, such as cognitive behavioural therapy (CBT)

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


The main symptom of complex regional pain syndrome (CRPS) is pain, which can sometimes be severe, continuous and debilitating.

It's usually confined to 1 limb, but can sometimes spread to other parts of the body.

Chronic pain

The pain of CRPS is usually triggered by an injury. But the pain is a lot more severe and long-lasting than would normally be expected.

The pain may feel like a mix of burning, stabbing or stinging. There may also be tingling 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 cause intense pain.

You may hear this described in the following medical terms:

  • hyperalgesia – feeling pain from pressure or temperature that would not 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.

These can include:

  • strange sensations in the affected limb – it may feel as if it 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

Very rarely, 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 
  • 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 a GP as soon as possible if you've been experiencing feelings of depression or suicide. They'll be able to provide help and support.

Or 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 a GP

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

CRPS can be difficult to diagnose. It's best to get help as soon as possible because early treatment can help reduce your painful symptoms.

Who can get it

Although complex regional pain syndrome (CRPS) is a recognised medical condition, 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 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 original injury site, 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.

Because of 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 conditions.

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

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

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

It's also been suggested that a person's genes may play a part in them developing CRPS after an injury.

But the precise role genes play in CRPS is unclear and it's very unlikely that 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. But this theory has been largely disproven.


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

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

  • blood tests to rule out an underlying infection or rheumatoid arthritis
  • an MRI scan to rule out underlying problems with your tissue or bones
  • an X-ray to rule out problems with the joints and bones
  • nerve conduction studies to rule out damage to nerves

A physical examination may also be carried out by a 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 does not increase your pain.

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


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

Referrals should ideally be made as soon as possible so treatment can be started quickly.


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 around 85% of people with CRPS slowly experience a reduction in their pain and some of their symptoms in the first 2 years.

But 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 4 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 here.


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 on activity management to help avoid peaks and dips in activity despite pain
  • continuing rehabilitation treatments at home, such as desensitisation techniques
  • accessing any support groups in your local area

Physical rehabilitation

Physical rehabilitation involves a number of different treatments.

The aim is to gradually allow you to increase your 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.

Too much or too vigorous exercise can aggravate the condition, so it's important for your therapy to be supported by a therapist with experience of CRPS.

Here are some techniques that may be used as part of your physical rehabilitation programme.


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

If you have CRPS, movement can often be difficult, as information the brain needs to perform movements is often missing or confused.

Techniques like mirror visual feedback and graded motor imagery aim to improve movements by retraining the brain for these missing or confused bits of information.

Pain relief

There are several medicines that may help treat CRPS. Your pain specialist will be able to discuss them 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.

But these medicines will be licensed to treat another condition and will have undergone clinical trials for this.

Doctors may choose to use an unlicensed medicine if they're thought to be effective and the benefits of treatment outweigh any risks.

Here are some of the main pain relief treatments.

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.

NSAIDs 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.

But 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 anticonvulsants include drowsiness, dizziness and weight gain.

There's also a small increased risk of suicidal thoughts, which may occur as early as a week after starting treatment.

Do not suddenly stop treatment with anticonvulsants as 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 usually 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 suddenly stop taking TCAs.

If you feel you no longer need to take them, your GP will arrange for your dose to be slowly reduced over a period of at least 4 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
  • thinking processes can be slower (cognitive problems)

Long-term use of high doses of opioids has been linked to more serious health 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.

Addiction to opioids is rare, but there's a risk you may become dependent on them.

This means your body and mind do not want to stop taking them, even if they're not very effective.

You may feel worse for a short period of time when you do reduce or stop taking them.

Spinal cord stimulation

A treatment called spinal cord stimulation may be recommended if medicine does not reduce your pain.

It 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. 

The 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 6 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, as 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 pain management programmes.

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.

Your care team

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

These include:

  • a physiotherapist, who can help you improve movement and coordination
  • an occupational therapist, who can help you improve the skills needed for daily activities
  • a pain relief specialist, a doctor or other healthcare professional trained in pain relief
  • a psychologist, a specially trained mental health professional who can help manage and understand some of the emotional impact association with long-term pain
  • a social worker, who can provide information and advice about extra help and services 
  • an employment adviser, who can offer support and advice to you and your employer to help you stay in, or return to, work
  • a GP, who can co-ordinate your care

These healthcare professionals may work with you either individually or jointly in pain management programmes.

The aim is to support you so you can manage the impact of pain on your life, even if the intensity of your pain cannot be reduced.

The information on this page has been adapted by NHS Wales from original content supplied by NHS UK NHS website
Last Updated: 26/10/2022 15:28:03