Pain and chronic conditions

Complex Regional Pain Syndrome (CRPS)

Expert-reviewed guidance on CRPS — why the pain is out of proportion to the injury, and why protecting the limb makes it worse.

  • Expert Reviewed
  • Evidence Based
  • Patient Focused

Dr. Eva Lassey, PT, DPT reviewed the exercise, movement, and rehabilitation content in this article. Information on diagnosis and medical management follows published guidance from the sources listed at the foot of this page. · View bio → · Last updated August 27, 2026

Ages covered on this page: Adults

Complex regional pain syndrome is a condition in which pain after an injury becomes far more severe and prolonged than the injury would explain, usually affecting a hand, arm, foot, or leg. Alongside the pain there are changes in the limb itself — differences in temperature or color, swelling, sweating, altered sensitivity, stiffness, and sometimes changes to hair, skin, or nails.⁠1 It can follow a significant injury or a minor one, and occasionally none at all.⁠2 Early recognition matters, because treatment usually works best when it starts early⁠1 and keeping the limb still can cause and prolong the problem.⁠3 Diagnosis is clinical, based on the pattern of signs and symptoms.

What is complex regional pain syndrome? Triggers and signs

A disorder of how the nervous system responds to injury. Its mechanisms are only partly understood; research points to changes in pain processing, the autonomic nervous system, inflammation, and the brain's representation of the limb.⁠3

The defining feature is disproportion. The pain, and the changes in the limb, are out of proportion to whatever started it.⁠3

  • It can follow a minor injury. A sprain, a cut, a broken wrist, or an operation — an injury that seemed mild can still lead to severe CRPS.⁠1
  • Sometimes there's no identifiable trigger at all, which doesn't make the diagnosis less valid.⁠2

Signs cluster in four groups, and diagnosis is based on a pattern across them:⁠3

  • Sensory — pain from light touch, increased pain from normally painful stimuli
  • Vasomotor — temperature or color differences between the limbs
  • Sudomotor or edema — swelling, or differences in sweating
  • Motor or trophic — reduced movement, weakness, tremor, or changes to hair, skin, or nails

CRPS was previously called reflex sympathetic dystrophy or causalgia. Those terms are largely retired.⁠3

Why moving the limb early matters in CRPS

This is the most important practical point on the page, and it runs against instinct.

The natural response to a painful limb is to protect it — hold it still, avoid using it, keep it covered. In CRPS, that protection makes things worse.

Keeping a limb still is recognized as a possible cause of CRPS and a factor that keeps it going: in healthy volunteers, four weeks in a cast produced CRPS-like changes in skin temperature, pain sensitivity and hair growth.⁠3 Not using the limb also brings stiffness and swelling of its own.⁠1

Treatment therefore aims at keeping the limb used and moving, at whatever level is tolerable, from as early as possible.⁠1,3 That is hard, and it needs support. Being told to move a limb that hurts to touch is not a small request, and it works best with a therapist who understands the condition.

How CRPS is treated: graded movement, mirror therapy and more

Rehabilitation is the core of guideline treatment, usually alongside pain management and psychological care,⁠3 although trials of individual physical therapy approaches are small and their effects remain uncertain.⁠5

  • Graded movement and use — keeping the limb in the picture, restoring function progressively.⁠3
  • Desensitization — graduated exposure to touch and texture, so the limb tolerates contact again.⁠3
  • Graded motor imagery — a staged approach working through recognizing limb laterality, imagined movement, and then mirror therapy. It targets the brain's representation of the limb, which is affected in CRPS.⁠3
  • Mirror therapy — using a mirror so the affected limb appears to move normally. Unusual-sounding; small trials suggest it and graded motor imagery can ease pain in CRPS, though the evidence is too limited to rank them above other treatments.⁠6
  • Pain education — guidelines recommend it for everyone with CRPS: what disuse does, and why getting the limb active again matters.⁠3
  • Psychological support — CRPS is distressing and can affect mood and sleep; cognitive behavioral therapy can help people cope and stay active.⁠1 Support is offered because the condition is hard, not because the pain is psychological.
  • Medical management — several approaches exist, and this is a conversation for a pain specialist. Referral to a specialist pain service is appropriate, particularly where symptoms aren't improving.⁠1,4

RelatedFind a physical therapistFind an occupational therapist

CRPS therapy goals, with examples

Tolerate a sock on that foot · Put my hand in my pocket · Wash the affected limb myself · Use the hand to hold a cup · Walk without a crutch

Reduce pain · Improve range of motion

"Tolerate a sock" is not a modest goal in CRPS. Allodynia — pain from light touch — is a core feature of CRPS,⁠1 and tolerating clothing is a genuine milestone.

CRPS recovery and prognosis: what to expect

  • Outcomes vary considerably. Pain and function often improve over time, especially in early CRPS, but most people still have some pain a year on, and a minority do not recover.⁠1,3
  • Progress is usually slow and non-linear, and flares are part of the course rather than a sign of failure.⁠3
  • Signs can come and go. The picture can change within one person over time, and diagnosis counts only the signs seen at the examination,⁠3 so a limb that looks normal in clinic may have looked very different that morning. Photographs of the limb during a flare are genuinely useful to bring to appointments.

Frequently Asked Questions

What is complex regional pain syndrome?

A condition where pain after an injury becomes far more severe and prolonged than the injury explains, with changes in the limb's temperature, color, swelling, sensitivity, and movement.⁠1

Can CRPS follow a minor injury?

Yes. A sprain, a cut, a broken wrist or an operation can trigger it, and an injury that seemed mild can still lead to severe CRPS. Occasionally there's no identifiable trigger.⁠1,2

Should I rest the limb?

No — and this is the most important point. Keeping a limb still is recognized as a possible cause of CRPS and a factor that keeps it going. Keeping the limb moving and in use, at whatever level is tolerable, is central to treatment.⁠1,3

What is graded motor imagery?

A staged rehabilitation approach working through limb laterality recognition, imagined movement, and mirror therapy. It targets the brain's representation of the limb, which is affected in CRPS.⁠3

Does mirror therapy really work?

Small trials suggest it can ease pain in CRPS, though the evidence is too limited to rank it above other treatments. Using a mirror so the affected limb appears to move normally is thought to address the altered representation of the limb.⁠3,6

Why does light touch hurt so much?

Allodynia — pain from stimuli that shouldn't be painful — is characteristic: the skin can hurt with light touch or normal contact. It reflects changes in how the nervous system processes touch.⁠1

How is CRPS diagnosed?

On a pattern across four groups of signs rather than on any single test: sensory (pain from light touch, increased pain from normally painful stimuli), vasomotor (temperature or color differences between the limbs), sudomotor or edema (swelling or differences in sweating), and motor or trophic (reduced movement, weakness, tremor, or changes to hair, skin or nails).⁠3

Will CRPS go away?

Outcomes vary. Pain and function often improve over time, especially when CRPS is treated early, but most people still have some pain after a year, and a minority do not recover.⁠1,3,4

Conditions and pages that commonly come up alongside CRPS.

Persistent pain

The wider picture on long-term pain, and what treatment can realistically offer.

Learn more →

Pacing and activity management

Building activity by planned amounts when symptoms make that hard.

Learn more →

Fibromyalgia

Another condition where the nervous system's pain processing is central.

Learn more →

Find an occupational therapist

Keeping the limb used in daily activities is occupational therapy's territory.

Learn more →

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Sources

  1. National Institute of Neurological Disorders and Stroke. Complex Regional Pain Syndrome. Checked October 6, 2026.
    Show the passageHide the passage
    CRPS “usually affects a limb (an arm or a leg) after an injury,” which may seem mild; light touch can be painful; skin, temperature, nail, hair and sweating changes; not using the limb causes stiffness and swelling of its own; “Treatment usually works best when it is started early”; gentle movement and physical therapy can be important; most people still have some pain after a year.
  2. de Mos M, de Bruijn AG, Huygen FJ, Dieleman JP, Stricker BH, Sturkenboom MC. The incidence of complex regional pain syndrome: a population-based study. Pain. 2007;129(1–2):12–20. doi:10.1016/j.pain.2006.09.008 (PMID 17084977). CRPS “can occur in an extremity after any type of injury, or even spontaneously”; a fracture was the most common precipitating event (44%).
  3. Harden RN, McCabe CS, Goebel A, et al. Complex regional pain syndrome: practical diagnostic and treatment guidelines, 5th edition. Pain Medicine. 2022;23(Suppl 1):S1–S53. doi:10.1093/pm/pnac046 (PMID 35687369).
    Show the passageHide the passage
    The diagnostic criteria (pain disproportionate to any inciting event; four sign groups; no better explanation); limb immobilization “is recognized as a possible cause and/or perpetuating factor”; interdisciplinary functional restoration, desensitization, graded motor imagery and education for all patients; early CRPS often improves, while about 15% fail to recover.
  4. Harnik MA, Kesselring P, Huber M, et al. Implementation of a fast-track pathway for complex regional pain syndrome: associations with referral delay and one-year clinical outcomes. Journal of Pain. 2026;49:106403. doi:10.1016/j.jpain.2026.106403 (PMID 42567237). After faster referral to specialist care, 62.1% improved at 12 months against 38.5% before; “Longer disease duration was associated with lower odds of improvement.”
  5. Smart KM, Ferraro MC, Wand BM, O’Connell NE. Physiotherapy for pain and disability in adults with complex regional pain syndrome (CRPS) types I and II. Cochrane Database of Systematic Reviews. 2022;(5):CD010853. doi:10.1002/14651858.CD010853.pub3 (PMID 35579382). Thirty-four trials: “The evidence is very uncertain about the effects of physiotherapy interventions on pain and disability in CRPS.”
  6. Méndez-Rebolledo G, Gatica-Rojas V, Torres-Cueco R, Albornoz-Verdugo M, Guzmán-Muñoz E. Update on the effects of graded motor imagery and mirror therapy on complex regional pain syndrome type 1: a systematic review. Journal of Back and Musculoskeletal Rehabilitation. 2017;30(3):441–449. doi:10.3233/BMR-150500 (PMID 27858687).
    Show the passageHide the passage
    Six trials, 171 participants: graded motor imagery and mirror therapy “can improve pain” in CRPS type 1, but there is “not sufficient evidence to recommend these therapies over other treatments.”

Medical disclaimer. This page is for general educational purposes and does not constitute medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider about your individual situation. Seek prompt assessment if pain after an injury is disproportionate or the limb has changed in color, temperature, or swelling.