A recent randomised controlled trial, published in eClinicalMedicine, aimed to investigate the effect of a high oral dose of CBD on chronic neuropathic pain associated with spinal cord injury. This blog details what the researchers did, what they found, and what the results do not yet tell us.
Key takeaways
- The trial tested high-dose CBD (increased gradually to 800 mg a day) against a placebo in 38 adults with long-standing nerve pain after spinal cord injury.
- On average, pain scores fell by 14% on CBD compared with 6.5% on placebo — a small but statistically significant difference.
- More people had a meaningful reduction in pain (at least 30%) on CBD than on placebo: 37.8% versus 11.1%.
- CBD was generally well tolerated. Most side effects were mild — most commonly tiredness, nausea and diarrhoea.
- The authors describe the benefit as modest and call for larger studies. This is one early-stage trial, not proof that CBD relieves nerve pain.
What is neuropathic pain?
Neuropathic pain is pain caused by damage to, or a problem with, the nervous system itself, rather than by an injury to tissue such as a cut or a bruise. People often describe it as burning, shooting or electric-shock-like. It is considered chronic when it lasts three months or longer. Nerve pain is common after spinal cord injury, and many people who live with it describe it as the most distressing consequence of their injury.
How is neuropathic pain usually treated?
Treatment usually combines medicines with non-drug approaches. Commonly used medicines include certain antidepressants and anticonvulsants. Psychological therapies, including cognitive behavioural therapy (CBT), can also help people manage long-term pain.
Even so, only around 40–50% of people achieve a meaningful (more than 50%) reduction in pain with current treatments, and side effects are common. This gap is one reason researchers continue to look for new options.
Why are researchers studying CBD for nerve pain?
CBD (cannabidiol) is one of the most abundant compounds in the cannabis plant. Surveys show that many people with spinal cord injury and nerve pain already use cannabis or cannabinoids to manage their symptoms, including related problems such as anxiety and low mood.
Laboratory studies suggest CBD might reduce neuropathic pain, but good-quality trials in people are limited. Two earlier trials using low oral doses found no significant effect on pain, while a single trial using a higher dose (120 mg a day) reported better pain relief than placebo. The 2026 study set out to test a much higher dose — up to 800 mg a day.
What did the study involve?
The study was a randomised, double-blind, placebo-controlled, crossover phase 2 trial carried out in Sydney, Australia. “Crossover” means each participant received both CBD and placebo at different times — six weeks on each, separated by a four-week break — so they acted as their own comparison. Neither the participants nor the research team knew which treatment was being taken at any given time.
Forty adults with spinal cord injury and nerve pain lasting at least three months took part, and 38 were included in the main analysis. The CBD dose was increased gradually over two weeks up to 800 mg a day. Participants rated their pain three times a day on a 0–10 scale (0 = no pain, 10 = the worst pain imaginable). The researchers also looked at secondary measures, including pain quality, the impact of pain on daily life, mood, anxiety and sleep.
What did the study find?
Pain intensity
On average, pain scores fell by 14% from the start to the final week of CBD treatment, compared with 6.5% during placebo. When CBD and placebo were compared directly, pain was modestly lower on CBD — a difference of about half a point on the 0–10 scale (95% confidence interval −0.88 to −0.21).
Who responded?
The clearest signal came from a “responder” analysis. More than a third of participants (37.8%) had at least a 30% drop in pain on CBD, compared with 11.1% on placebo. People with longer-standing injury and pain tended to respond more strongly.
Other measures
CBD did not show a clear benefit over placebo for the secondary measures — such as mood, anxiety, sleep or quality of life. Average anxiety and depression scores were low to begin with, however, which makes any effect on those measures harder to detect.
How should these results be interpreted?
The findings are encouraging but should be kept in perspective. The average 14% reduction in pain is below the threshold usually considered moderately clinically meaningful (around 30%), and is closer to what researchers call a “minimal” improvement. The trial was also small, included far more men than women, and most participants were taking several other medicines — which raises the possibility of interactions with CBD.
Even so, this is the first trial to test high-dose CBD specifically for nerve pain after spinal cord injury. Its main value is in showing that the approach is worth investigating in larger studies, and that some people may respond better than others.
Were there any side effects?
Across the trial, 119 side effects were recorded, and nearly all were mild. Slightly more were reported during CBD treatment (in about 68% of participants) than during placebo (about 53%). The most common during CBD were unusual tiredness or sleepiness, nausea, diarrhoea, feeling unwell and loss of appetite. Two people left the study because of side effects — one taking CBD (nausea) and one taking placebo.
What happens next?
The researchers conclude that high-dose CBD appears safe and may help reduce nerve pain in some people, and that larger trials are now justified. Notably, of those who did not gain a clinically meaningful benefit during the trial, 10 still said they would want to continue CBD afterwards.
Thinking about treatment options?
In the UK, cannabis-based medicines are prescription-only and remain unlicensed for most conditions. They can only be prescribed by a specialist doctor. This is usually when licensed treatments have been tried and have not worked well enough. They are not suitable for everyone either.
This article is for general information only. It is not medical advice, and it is not a recommendation to use any specific medicine. If you would like to understand whether a specialist consultation might be appropriate for you, a qualified clinician can review your medical history and discuss your options with you. You can complete our online eligibility check for a consultation to find out more.
