Ontario doctors are still hesitant to prescribe medical cannabis to patients suffering long-term pain 20 years after it was first introduced, says a new study carried out at McMaster University.

Physicians surveyed said their main concerns relate to possible ill-effects and a lack of understanding regarding their effectiveness as painkillers.

Of particular concern among doctors were potentially harmful effects on cognitive development, a possible worsening of existing mental illnesses in patients and the drug’s effects in older adults, which may include dizziness or drowsiness.

Meanwhile, the number of Canadians using medical cannabis has soared from just under 24,000 in June 2015 to 377,000 by September 2020.

“This paper is demonstrating that there is a real perceived need by family physicians that more evidence, education and guidance is needed, so they can better help patients who are asking about this treatment,” said Jason Busse, associate director of the Michael G. DeGroote Centre for Medicinal Cannabis Research at McMaster.

All 11 doctors surveyed said medical cannabis can relieve chronic pain. Some also suggested it may help relieve multiple sclerosis, nausea and vomiting caused by chemotherapy, stimulating patients’ appetites, as well as easing insomnia and anxiety.

However, doctors are still hampered by a lack of proper guidance, while medical cannabis products have not undergone the same rigorous trials as other pharmaceutical drugs on the market, said Busse, associate professor of anesthesia.

In 2019, the Canadian Medical Association said that although cannabis may offer patients relief when conventional therapies fail, a lack of evidence surrounding the risks and benefits of its use makes it difficult for physicians to advise patients properly.

Elsewhere, the jury is still out on medical cannabis. The US-based National Academies of Sciences, Engineering, and Medicine ruled that patients treated with medical cannabis are more likely to gain some pain relief, but Britain’s National Institute for Health Care and Excellence has made a strong recommendation against using it to relieve chronic pain.

Six of the physicians surveyed also raised the issue of how legal recreational cannabis affected its medical counterpart, but 10 said therapeutic variants should remain an option. Recreational cannabis, which has different formulation than medical cannabis, was legalized in Canada in October 2018.

Legal cannabis means easier regulations, ever-higher numbers of cannabis producers, greater availability and reduced stigma about using cannabis for medical use, says the report.

“When you have such widespread recreational and medical cannabis use, there is a real challenge for healthcare providers who are not trained in prescribing it,” said Busse.

Researchers conducted telephone interviews with the doctors between January and October 2019 and published their findings in the Canadian Medical Association Journal Open this month.

No external funding was received for this study.