High-dose CBD reduced chronic neuropathic pain in a placebo-controlled clinical trial conducted by researchers from the University of Sydney, who said the trial produced “strong results” for a condition that remains notoriously difficult to treat.
Published in The Lancet’s eClinicalMedicine, the trial involved 40 adults with spinal cord injury-related neuropathic pain, with 38 included in the primary analysis.
The study involved escalating doses of CBD tablets, beginning at 200mg per day and increasing to 800mg per day by the end of the trial.
Researchers found participants taking CBD over a six-week period reported an average reduction in pain of around 14%, compared with 6.5% among individuals taking a placebo.
Significantly, almost 38% of participants achieved a reduction in nerve pain of at least 30%, a threshold commonly regarded as clinically meaningful.
Lead author Dr Rebecca Robertson, from the University of Sydney’s Brain and Mind Centre, said the findings exceeded expectations.
“Chronic neuropathic pain is notoriously hard to treat, with traditional therapies ineffective in about 50% of cases,” she said.
“To see such strong results in the trial is significant and suggests there is real potential for CBD to be used to help manage chronic neuropathic pain.”
Researchers said CBD was generally well tolerated, with most adverse events described as minor. Common side effects included tiredness, nausea and diarrhoea.
The researchers noted that participants remained on a range of existing medications during the trial, meaning potential drug interactions may have influenced the results.
They also said the possibility that participant expectations influenced outcomes could not be ruled out, with 78% of participants correctly identifying when they were taking a placebo.
Co-investigator Professor Iain McGregor said researchers were now looking to better understand why CBD appeared to work better for some patients than others.
“Further work is needed to understand why CBD worked better for some people than others, and also to understand how CBD might interact with other medications that participants were taking,” McGregor said.
“In the long term, we hope this work will lead us towards developing treatments to manage pain more effectively.”
The trial was funded by NSW Health and the Lambert Initiative for Cannabinoid Therapeutics at the University of Sydney.
