The following opinion piece was published in The Australian on 27 March 2018.

Many people trust medicinal cannabis to help patients with a wide range of conditions and relieve symptoms associated with debilitating illness such as cancer and childhood epilepsy.
 
A special access scheme allows doctors to seek medicinal cannabis products for their patients, noting they are not registered for prescription. Anecdotally, we hear that some doctors can organise access for patients within days, with relevant government approvals.

While some governments are seeking to make it easier for people to access medicinal cannabis, there are still legitimate concerns about its use, particularly in the absence of robust clinical studies.

Some of Australia’s best researchers have undertaken a systematic review and meta-analysis of the body of research carried out in Australia and overseas examining the evidence of the effectiveness and safety of cannabinoids in treating a wide range of medical conditions, where they are believed to offer therapeutic benefit.

They identified a lack of rigorous, high-quality and reproducible human data to guide clinicians. They also found that much of the data gathered in these studies was derived from poorly designed observational studies, as opposed to more reliable, randomised controlled trials.

Where benefits of medicinal cannabis were found, it was often considered to be quite small or inconsistent when compared with a placebo. Also, in many of these studies, the drugs against which it was compared have long been superseded.

Researchers have found other reasons for caution, given the common side effects and significant adverse events associated with medicinal cannabis. This isn’t to say that one or more cannabinoids will not provide therapeutic benefit in certain medical conditions including the clinical management of intractable forms of childhood epilepsy.

Some patients may feel they are getting relief, but this may be because of the psychoactive effects rather than treating the disease-specific symptoms of the condition, for example if it’s a THC combination product using active ingredients from cannabis. Across time this can create new problems.

As doctors, we want to be cautious and learn from the past, for example our experience of opioid usage. Today, we’re facing an opioid epidemic, we are becoming increasingly aware of the significant risks and harm associated with these medicines.

There’s another potential risk with using medicinal cannabis. People may stop other treatments that are benefiting them because they believe cannabis a better option.

If we want new and better treatments using medicinal cannabis, we still need high-quality, replicated clinical trials to carefully assess the effectiveness of medicinal cannabis, and this needs to be balanced against the potential unwanted adverse events that can travel with this drug.

The evidence for using medicinal cannabis isn’t strong or convincing to the degree that we should believe it to be the answer for which so many hope.

There is a great deal of work going on in research behind the scenes in Australia and the sense of urgency is understandable. But we owe it to patients to temper this enthusiasm with good science.

For now, doctors should use effective, tried and tested methods before considering medicinal cannabis. Regulators and decision-makers need to monitor outcomes closely to create an evidence base and ensure any adverse events, side effects and outcomes are accurately reported.

Associate Professor Adrian Reynolds is president of the chapter for addiction medicine at the Royal Australasian College of Physicians.