In a remarkably short period, the landscape of medicine in Australia has been reshaped by the rapid rise of medicinal cannabis. Since access pathways were expanded in 2016, a staggering 700,000 prescription approvals have been issued, marking a dramatic increase in its use across the country. Yet, this prescribing boom has occurred largely outside the standard regulatory framework, with the vast majority of medicinal cannabis products not registered on the Australian Register of Therapeutic Goods. This has created a paradoxical situation where many patients are reporting benefits, while professional bodies and regulators are raising concerns that prescribing is “outpacing the evidence.” The three most common conditions for which it is prescribed are chronic pain, anxiety, and sleep disorders. But the question remains: does the evidence truly support this widespread use?
Defining Medicinal Cannabis and Its Use
To understand the evidence, it’s essential to first define what medicinal cannabis is. It refers to cannabis products that are legally prescribed for a medical condition. This can include the plant itself, natural compounds extracted from it, or lab-made compounds that are similar to or the same as those found in the plant, such as dronabinol and nabilone. The plant contains a variety of compounds, but the two most common are THC (tetrahydrocannabinol) and CBD (cannabidiol), collectively known as cannabinoids.
These cannabinoids are found in varying concentrations in medicinal cannabis products, which come in a range of forms to suit different patient needs. The most common forms include oils, capsules, sprays, and gummies, as well as dried flower which is used in a vaporiser. While the products and their formulations are diverse, the reasons for their prescription are remarkably concentrated. Data from the Therapeutic Goods Administration (TGA) reveals that the three most common conditions for which scripts are approved are chronic pain, anxiety, and sleep disorders, a trio of ailments that affect a large portion of the population.
Pain Relief: Modest Benefits, Limited Evidence
Chronic pain is by far the most common reason for medicinal cannabis use in Australia. Many patients report a subjective benefit from its use, but the scientific evidence paints a more cautious picture. Research has consistently shown that the benefits of medicinal cannabis for chronic pain are only modest, offering “limited improvements” in both pain reduction and physical functioning. This means that while some individuals may experience a degree of relief, it is often not a “clinically significant” change.
The TGA, in its official guidance, has stated that there is limited evidence for medicinal cannabis providing substantial pain relief for many conditions. It is therefore recommended that it should only be considered as a last resort, after other standard therapies have been tried and have not been successful. This position highlights a significant discrepancy between the widespread practice of prescribing for pain and the current state of scientific consensus, urging both prescribers and patients to proceed with caution and a clear understanding of the evidence base.
Navigating the Ambiguity of Anxiety
Alongside chronic pain, a rapidly increasing number of people are turning to medicinal cannabis as a treatment for anxiety. This growing trend is once again outpacing the conclusive scientific evidence. When it comes to THC-based products, the evidence is decidedly mixed. While some patients report finding relief from their symptoms, an equal number have reported that their anxiety symptoms have actually worsened. This ambiguity makes it difficult to draw firm conclusions or make clear recommendations for its use.
For CBD, the evidence is still considered “emerging”. While some studies have shown positive effects, particularly in experimental conditions designed to induce stress, these studies have major limitations. They are often small, lack a control group, or only test a one-off dose, making it impossible to determine if CBD is effective for long-term anxiety management. A recent review even found that the reported positive effects of CBD were only seen in studies with methodological problems. Furthermore, there have been recent case reports of acute psychosis arising from medicinal cannabis use, adding another layer of risk to the already ambiguous evidence. Taken together, the role of cannabinoids for anxiety remains far from clear.
Sleep Disorders: Drowsiness vs. Quality
The evidence for the use of medicinal cannabis for sleep disorders and insomnia is arguably even more limited. Studies have not been able to show clear benefits for either CBD or THC in terms of reducing the number of awakenings, decreasing time spent awake during the night, or improving overall sleep quality. While some individuals do report feeling that their insomnia symptoms have been reduced, this is often a subjective feeling of drowsiness rather than a measurable improvement in sleep architecture.
The short-term sedative effects of THC can indeed make a person feel drowsy and may help them fall asleep faster. However, there are important downsides to consider for long-term use. Regular use of medicinal cannabis can lead to dependence, making it harder for the body to fall asleep without it. Additionally, in the long term, medicinal cannabis can affect the amounts of light and deep sleep a person will have, which can result in poorer sleep quality. This highlights a critical distinction: just because a substance makes you feel sleepy doesn’t mean it is a good treatment for a sleep disorder.
Where the Evidence Stands Strong
While the evidence for the most common uses of medicinal cannabis is limited, there are some specific conditions for which the evidence is robust and well-established. Some of the strongest evidence for the efficacy of medicinal cannabis products is for rare forms of epilepsy that do not respond to existing treatments, as well as for treating symptoms associated with multiple sclerosis.
In fact, the only medicinal cannabis products that have received TGA approval and are on the Australian Register of Therapeutic Goods are for these specific conditions. There is also strong evidence that medicinal cannabis can help with chemotherapy-induced nausea and vomiting. However, because newer medications with fewer side effects are now available, medicinal cannabis products are not considered first-line treatments for this purpose, a testament to the ongoing evolution of medical science and pharmacology.
Risks and Long-Term Considerations
As with any medication, there are risks and side effects associated with the use of medicinal cannabis. In the short term, common side effects with THC can include drowsiness, dry mouth, nausea, vomiting, and appetite changes. For some individuals, these effects may reduce over time as their body adjusts. However, people with preexisting health conditions, such as schizophrenia, psychosis, or heart conditions, may be more prone to experiencing these side effects, and should approach its use with extreme caution.
Perhaps the most significant long-term risk is the potential for dependence. An estimated one in four people using medical cannabis meet the criteria for dependence, also known as cannabis use disorder. This dependence appears to be more common with medical use, particularly when it is combined with non-medical use. This important risk factor, along with the ambiguous evidence for its most common uses, is a key concern for regulators and health professionals, who urge for more rigorous research to truly understand the full scope of medicinal cannabis’s benefits and risks.
