Can you get medical cannabis for complex regional pain syndrome in the UK?

Complex regional pain syndrome is rare, severe, and badly served by the treatments available. Pain is out of proportion to the original injury, and the standard options — physiotherapy, neuropathic pain medicines, nerve blocks — often fall short. That is the setting in which UK specialists consider a cannabis-based medicine, on the thinnest evidence base on this site.

Is complex regional pain syndrome treated with medical cannabis in the UK?

It is considered, individually, and almost always in people who have already been through specialist pain services without adequate relief. It is not an NHS treatment for CRPS and no product is licensed for it.

CRPS usually follows an injury or surgery and produces burning pain, swelling, changes in skin colour and temperature, sensitivity to light touch, and loss of function in the affected limb. UK practice, set out in Royal College of Physicians guidance, is built around early multidisciplinary care: physical rehabilitation, pain management, and psychological support together, with medicines playing a supporting role rather than a leading one.

A specialist considering a cannabis-based medicine for CRPS is looking for something that makes rehabilitation possible — not something that replaces it. If pain relief comes at the cost of engagement with physiotherapy, it has not helped.

What the evidence actually shows

This is the weakest evidence base on this site. There is no randomised controlled trial of cannabis-based medicines in complex regional pain syndrome. What exists is a small UK case series and indirect evidence borrowed from the neuropathic pain literature.

Researchers analysing the UK Medical Cannabis Registry published a clinical outcomes analysis for CRPS patients, tracking patient-reported pain, sleep, anxiety and quality-of-life measures over six months. It reported improvements across those measures with adverse events that were mostly mild or moderate. As a case series with no control group, it cannot distinguish the medicine from the natural course of the condition, from regression to the mean in people who enrolled at their worst, or from the effect of expectation. The authors say as much.

Anyone telling you the evidence for CRPS is strong is not describing the literature.

What a specialist will want to see

There is no UK list of qualifying conditions, so nothing here entitles you to a prescription. A specialist works through your history and decides whether a monitored trial is justified for you. For complex regional pain syndrome they will typically look at:

• Whether CRPS has been formally diagnosed, and against which criteria
• Whether you have been seen by a specialist pain service and what that involved
• Which neuropathic pain medicines you have tried — and nerve blocks or other interventions, if offered
• How you are getting on with physical rehabilitation, and what is stopping you
• The psychological impact, which in CRPS is substantial and is treated as part of the condition, not a side issue
• Your other medicines, and your personal and family history of psychosis

The general requirements — age, a documented diagnosis, the convention that two standard treatments have been tried, and access to your medical records — are covered in What are the requirements?

Risks and reasons a specialist may say no

With evidence this thin, the main risk is a mismatch between hope and outcome. CRPS is a condition where people have often been let down repeatedly, and a specialist who promises a result rather than a trial is not being straight with you.

The pharmacological risks are the usual ones: drowsiness, dizziness, impaired concentration, dry mouth and driving impairment from THC-containing products. Sedation matters more than usual here, because anything that reduces your capacity for physical rehabilitation works against the treatment that has the best evidence behind it. Personal or family history of psychosis, unstable mental illness, pregnancy and breastfeeding all count against treatment.

How medical cannabis is thought to help

The body has an endocannabinoid system — a network of signalling molecules and receptors woven through the nervous system that helps regulate how pain is processed, along with sleep and mood. Cannabis-based medicines contain compounds that interact with this system, and because CRPS involves amplified, disordered pain signalling, the working idea is that this might be modulated.

In CRPS more than anywhere, it is worth being clear about what that means. There is no randomised trial evidence, so a plausible mechanism carries no promise of relief for you, and the honest aim is usually to make rehabilitation possible rather than to remove pain. The two main compounds are thought to act differently, one intoxicating and more associated with pain and sleep effects, the other not intoxicating, and a specialist balances them for you. The biology is set out plainly in the endocannabinoid system explained and THC and CBD explained.

What treatment involves in practice

Where a specialist decides a trial is justified, it starts at a low dose that is increased slowly under supervision. In CRPS the balance to strike is finding relief that supports movement without sedation heavy enough to undercut physical rehabilitation, which remains the approach with the strongest support in UK guidance.

The usual formats are oils or capsules taken by mouth, which act more slowly and last longer, and dried flower for vaporising, which acts faster but fades sooner; neither is smoked. How each is used is covered in how cannabis-based medicines are taken, and how a starting point is chosen and changed is explained in how a dose is decided and adjusted. Any trial should run alongside your multidisciplinary pain care, not instead of it.

Follow-up reviews check whether pain, sleep and function have improved and whether you are able to rehabilitate, weighing that against side effects, and treatment is adjusted or stopped if the balance is wrong. Living with a prescription day to day also raises practical questions about driving and work and drug testing, each covered in its own guide.

Questions worth asking your specialist

With evidence this thin and a condition this difficult, a few direct questions help keep any trial honest and centred on function.

• Given there is no trial evidence in CRPS, what realistic improvement should I aim for?
• How would a trial support my physical rehabilitation rather than compete with it?
• Which format do you suggest starting with, and why for me?
• How will this be coordinated with my specialist pain service?
• At what review point would we decide to continue, adjust or stop?
• How will my GP be kept informed, and does shared care apply?

If you want to take this further

The useful next step is a proper assessment, not a better list. Gather your diagnosis, the treatments you have already tried and what happened with each, and your current medicines — that is what a specialist needs in order to give you a straight answer.

The consultation itself, and what happens after it, is set out in What is the process to get a medical cannabis prescription? If complex regional pain syndrome is not the only thing you are being treated for, say so early: other conditions and other medicines change the assessment.

Patient guide · Written by the Flora House editorial team · Last reviewed: 7 October 2026