A new study by researchers at the University of Sydney has shown that taking cannabidiol (CBD) can significantly reduce chronic neuropathic pain in those suffering from it. 

The findings of the randomised placebo-controlled trial, published in The Lancet eClinicalMedicine, demonstrated that taking CBD over a six-week period reduced pain by approximately 14 percent, compared to 6.5 percent from the placebo. 

CBD is a substance derived from the cannabis plant. Unlike tetrahydrocannabinol or ‘THC’ it does not cause a high. In Australia, CBD is a prescription-only medication that is currently used to treat conditions such as drug-resistant epilepsy.

Lead author Dr Rebecca Robertson, from the Brain and Mind Centre, said the results of the study were beyond what she expected: 

While the researchers found that pain reduced on average by 14 percent, some trial participants reported a greater than 30 percent reduction in nerve pain when taking CBD. 

In addition to the pain reduction reported by the trial participants, CBD was well tolerated at high doses with few serious side-effects.  

How researchers carried out the trial

The research team recruited 40 adults aged 18 or over who experienced chronic neuropathic pain as a result of a spinal cord injury – though the researchers stress that the findings are relevant to all people who experience chronic neuropathic pain, not only those experiencing it as a result of a spinal cord injury. Around 8.5 percent of Australians are estimated to live with chronic neuropathic pain. 

Participants received either CBD tablets or a placebo tablet which matched the CBD tablet in look, taste and smell. They took the tablets every day, with the dose in the CBD tablet increasing over time from 200mg per day at the beginning of the trial to 800mg per day at the end. 

Throughout the trial, participants were asked to complete a questionnaire three times a day on alternate weekdays, scoring their pain levels using a Visual Analogue Scale going from 0 (no pain) to 10 (worst pain imaginable). This scale is a widely used clinical tool for measuring subjective experiences like pain. 

Considerations from the study 

Alongside the trial medication of CBD or a placebo, participants were also taking a wide range of medications to manage not only their spinal cord injury but other conditions. As CBD may interact with commonly prescribed medications, it is possible that these interactions could have had an impact on the pain reduction reported. 

In addition, as 78 percent of the patients taking a placebo correctly guessed which tablet they were receiving, there is a possibility that those taking the placebo had lower expectations of the pain reduction they were likely to experience. 

Next steps 

Professor Iain McGregor, the study’s co-investigator said that he hopes the trial will pave the way for further research into the use of CBD in managing pain: 

“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.

“In the long term, we hope this work will lead us towards developing treatments to manage pain more effectively.”