Understanding Cannabis: The Risks of Unregulated Use and the Value of Medical Prescriptions

What is Cannabis?

Cannabis, also known as marijuana or weed among other names, is a psychoactive drug derived from the Cannabis plant. It’s native to Central or South Asia and has been used both recreationally and in traditional medicines for centuries. 

However, in Australia, cannabis remains the most widely used illicit drug. As of 2019, 36% of Australians aged 14 and over report they have tried cannabis at least once in their lifetime, and 11.6% report they had used it in the previous year. The rate of reported cannabis use has seen changes over the years, with a slight increase in both lifetime and recent use between 2016 and 2019. 

The primary psychoactive component in cannabis is Tetrahydrocannabinol (THC), although the plant contains at least 65 other cannabinoids, including Cannabidiol (CBD). THC is the psychoactive component that produces the ‘high’ associated with recreational use, whereas CBD is non-psychoactive.

The prescription of medical cannabis for therapeutic purposes is highly regulated, and only considered when other treatments have not been effective. Medical cannabis refers to the use of the cannabis plant, or its basic extracts, as a form of medication prescribed by doctors to treat certain conditions or alleviate symptoms. 

In many countries, including Australia, its legality and the conditions it can be prescribed for vary. The different forms of medical cannabis available include oils, capsules, pastilles (also known as chews or gummies) and topicals, rather than the smoked form commonly associated with recreational use.

The High Risks Of Cannabis Usage

While medical cannabis offers potential benefits for certain conditions, there are also risks to consider. 

A comprehensive analysis of randomised controlled trials and observational studies highlights several potential risks. Cannabis-based medicines may lead to increased adverse events related to the central nervous system, psychological effects, and vision issues in people with mixed conditions. 

Known risks of cannabis usage

Impaired Cognitive Function

Medical cannabis can impact cognitive functions, with effects that vary depending on several factors such as the amount of tetrahydrocannabinol (THC) present, frequency of use, age at first use, and whether other substances are used concurrently. Research indicates that recent use of marijuana can immediately affect thinking, attention, memory, coordination, movement, and time perception in both youth and adults.

Long-term effects of marijuana on the brain, particularly in young individuals, are of significant concern. Developing brains, including those of babies, children, and teenagers, are especially susceptible to marijuana’s harmful effects. Studies have suggested that marijuana use during pregnancy could result in attention, memory, problem-solving skills, and behavioural issues in children. 

Furthermore, initiating marijuana use before age 18 may impair the brain’s development, affecting functions such as attention, memory, and learning. These effects may be long-lasting or even permanent, highlighting the importance of further research to fully understand marijuana’s impact on brain development and cognitive functions.

Mental Health Issues

Cannabis use may increase the risk of developing mental health problems, such as psychosis or schizophrenia, particularly in people who are predisposed to these conditions. For conditions like chronic pain and epilepsy, while cannabis-based medicines may provide relief to the symptoms, they may also increase psychological distress and gastrointestinal issues, among other side effects.

Frequent usage of cannabis use in high doses can lead to disorientation and sometimes cause unpleasant thoughts or feelings of anxiety and paranoia. Users are also at a higher risk of developing temporary psychosis, characterised by a loss of touch with reality, hallucinations, and paranoia. 

Given these potential outcomes, it’s crucial for individuals, particularly those with existing mental health issues or a predisposition to psychiatric disorders, to consider the potential risks of cannabis use. Health professionals and patients should engage in open discussions about the possible mental health implications of cannabis, weighing its therapeutic benefits against the risks of negative psychiatric outcomes.


Medical cannabis may play a role in addiction therapy, particularly opioid addiction, through its interaction with the brain’s endocannabinoid system and its ability to modulate pain, mood, and reward pathways. The main psychoactive component of cannabis, THC, mimics the body’s natural endocannabinoids, which play a role in pain, mood, memory, and other physiological and cognitive processes. 

By activating cannabinoid receptors, THC can disrupt normal brain communication, altering mood and perception, which can have therapeutic effects for some individuals. For example, THC’s ability to mimic the endocannabinoid anandamide allows it to affect brain areas that influence pleasure, memory, thinking, and coordination, potentially offering relief from the symptoms of various conditions, including addiction​​.

Cardiovascular Issues

Medical cannabis, or marijuana, may negatively affect cardiovascular health in several ways, according to current evidence. Studies have found an association between marijuana use and an increased risk of cardiovascular events, including heart attacks and strokes. 

THC, the psychoactive compound in cannabis, can cause an increase in heart rate and blood pressure. This can be problematic for people with pre-existing heart conditions like coronary artery disease, angina, or heart failure.

Additionally, some studies suggest cannabis use may impair the function of the endothelium, the inner lining of blood vessels. This could potentially contribute to the development of atherosclerosis, or hardening of the arteries.

Drug Interactions

Medical cannabis can potentially interact with other medications, posing a risk for unintended effects or reduced effectiveness. The clinical relevance of drug interactions with cannabis varies, with some combinations posing high risks. For example, cannabis and warfarin interactions are classified as very high risk due to significant increases in INR levels, indicating a need for close monitoring.

Cannabis can interact with the way the body metabolises certain medications. This can lead to either increased or decreased effects of the medication, potentially causing unwanted side effects or reduced therapeutic benefits.

Cannabinoids in cannabis can interact with enzymes in the liver responsible for metabolising many medications. This can alter how quickly the body breaks down these medications, affecting their potency and duration of action. THC can interact with medications that depress the central nervous system (CNS). This can lead to additive effects, potentially causing excessive drowsiness, dizziness, or impairment.

When considering medical cannabis, it’s crucial to disclose all medications you’re currently taking to your doctor. They can assess the potential for interactions and advise on the safety of using medical cannabis in your specific situation.

The Importance Of Getting The Right Prescription For Medical Cannabis In Australia

In Australia, medical cannabis access is legal but tightly controlled. Obtaining the right prescription requires careful consideration by both patients and healthcare professionals. Here’s why securing an appropriate prescription is crucial:

Medical cannabis isn’t a one-size-fits-all solution. Different conditions and individuals respond better to specific cannabinoid profiles (ratios of THC and CBD) and product forms (oils, pastilles, etc.). The correct dosage is crucial for effective symptom management. An experienced healthcare professional can determine the appropriate starting dose and adjust it as needed to achieve optimal results.

Moreover, as previously mentioned, medical cannabis can interact with other medications and has its potential side effects. A proper consultation with a healthcare professional is essential to consider your medical history and current medications to reduce the risk of prescription interactions and adverse effects. 


In conclusion, the landscape of cannabis use, particularly for medicinal purposes in Australia, underscores the importance of thorough understanding and regulation. As the most widely used illicit drug, cannabis presents various risks including cognitive impairment, mental health issues, addiction, cardiovascular concerns, and potential drug interactions. 

These factors reinforce the necessity of obtaining an appropriate prescription, which ensures tailored treatment plans that consider individual health profiles and mitigate potential adverse effects. Proper medical oversight is paramount for harnessing cannabis’s therapeutic benefits while safeguarding against its risks.

Written by

Priyom holds a Ph.D. in Plant Biology and Biotechnology from the University of Madras, India. She is an active researcher and an experienced science writer. Priyom has also co-authored several original research articles that have been published in reputed peer-reviewed journals. She is also an avid reader and an amateur photographer.

Written by

Priyom holds a Ph.D. in Plant Biology and Biotechnology from the University of Madras, India. She is an active researcher and an experienced science writer. Priyom has also co-authored several original research articles that have been published in reputed peer-reviewed journals. She is also an avid reader and an amateur photographer.

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