Medicinal cannabis can significantly benefit the treatment of nerve pain underlying conditions such as multiple sclerosis and diabetes, according to a review of existing evidence on its clinical effectiveness and safety.
The finding by the Health Research Board (HRB) is likely to see the existing Medicinal Cannabis Access Programme expanded to include the treatment of neuropathic or nerve pain conditions.
The study found evidence to support the prescribing of medicinal cannabis for conditions for which it is already approved in Ireland – such as nausea and vomiting in cancer and spasticity in multiple sclerosis.
“There was also evidence of a significant benefit for neuropathic or nerve pain, which can occur with conditions such as multiple sclerosis, diabetes or spinal cord injury,” according to the HRB.
For other conditions, including anxiety and pain in conditions such as cancer, rheumatic diseases and fibromyalgia, the review found no conclusive evidence to confirm the efficacy of prescribed medicinal cannabis.
On safety, it found that although serious side effects do not appear to be common, there is some evidence of side effects such as dizziness, dry mouth, sedation, and headache. “Mixed evidence was found, however, on the likelihood of other adverse events such as drowsiness, nausea, and any psychiatric disorder adverse events.”
The study was conducted to inform an ongoing Department of Health review of the current Medicinal Cannabis Access Programme (MCAP).
The Department of Health set up MCAP in 2019 after a campaign by parents unable to access medicinal cannabis in Ireland for their sick children. It allows a consultant to prescribe a cannabis-based treatment for a small number of conditions, where the patient has not responded to standard treatments. The conditions are spasticity associated with multiple sclerosis, intractable nausea and vomiting associated with chemotherapy, or severe, refractory (treatment-resistant) epilepsy.
The HRB review looks at adult studies only and therefore did not assess the use of medicinal cannabis to treat children with severe epilepsy.
HRB chief executive Dr Mairead O’Driscoll said it was essential that healthcare policy is informed by the latest evidence, “including in areas where existing research is not sufficiently developed to draw robust conclusions”.
“By conducting this kind of review over time, the HRB can continue to provide policymakers with evidence to inform their decisions as research evolves.”
According to lead author Dr Kathryn Lambe, the review showed “some evidence” to support the use of medicinal cannabis in conditions such as nausea and vomiting due to chemotherapy, spasticity in multiple sclerosis, and managing neuropathic pain. “However, for most other outcomes, the findings were inconsistent at best.”