Cannabis-based medicines do not provide relief for people living with chronic neuropathic pain, according to a new review of research.
Neuropathic pain is caused by damage to the nerves and can be difficult to manage. It’s often linked to conditions such as diabetes, shingles, multiple sclerosis and spinal cord injuries.
Currently, existing medicines only help a small number of people, prompting experts to look for alternative options. Interest in cannabis-based medicines has grown in recent years – these treatments can be inhaled, taken as tablets or applied to the skin via creams or patches.
Researchers from the Cochrane Collaboration analysed 21 clinical trials involving more than 2,100 adults with long-term neuropathic pain. The studies compared cannabis-based medicines with placebo treatments over periods ranging between two to 26 weeks.
The medicines were divided into three groups and one mainly contained the chemical responsible for the ‘high’ linked to cannabis – this is otherwise known as tetrahydrocannabinol (THC).
Another medicine contained cannabidiol (CBD), which does not cause intoxications and a third group contained a mix of both THC and CBD.
Across all three types, researchers found no high-quality evidence that the treatments reduced pain better than a placebo.
It should be noted that some people taking medicines containing both CBD and THC reported small improvements, but these were not big enough to be considered meaningful.
The review also highlighted concerns about side effects, revealing that unwanted effects varied across the studies which made it difficult to assess the overall level of harm.
However, medicines containing THC were linked to symptoms such as dizziness and drowsiness and there was some evidence showing more people stopped taking the treatment early because of the side effects.
Winfried Häuser, clinician and lead author of the study, said: ‘We need larger, well-designed studies with a treatment duration of at least 12 weeks that include people with comorbid physical illnesses and mental health conditions to fully understand the benefits and harms of cannabis-based medicines.
‘At present, the quality of most of the trials is too poor to draw firm conclusions.’
The authors concluded the review, which can be accessed in full here, by claiming more research is needed before cannabis-based medicines can be recommended.
Image: Rick Proctor/UnSplash
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