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Medicinal Cannabis FAQ with Dr Stephen Chalk

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As interest in medicinal cannabis continue to climb and the number of active patients grow, more questions regarding cannabis products are beginning to surface.
We were lucky enough to have the opportunity to chat with Dr Stephen Chalk based in Western Australia - who has had extensive experience with medicinal cannabis. He kindly agreed to answer some questions we gathered from a community of potential and active cannabis patients.
Please be mindful the answers below are published for educational purposes only. Cannabis can affect individuals in different ways, please consult with your doctor before using medicinal cannabis products.

Tell us about your journey as a health professional with an interest in medicinal cannabis

Like most of the medical staff in Perth’s northern suburbs, I’m originally from the UK. I studied in Oxford and London, and worked as a junior doctor in the south of England for a few years before heading to WA for a working holiday. Needless to say I settled into the sunny lifestyle and never left. I spent a few years in Emergency Medicine training, which included a brief anaesthetics stint. I then switched to GP training to better suit my family. As a GP I split my time between a busy suburb and a semi-rural town, so I get a great mix of patients. I’m able to indulge my interests in addiction, skin cancer, minor surgeries and pain management.

"There is such a vast amount of fascinating science around the chemistry, botany, pharmacology and genetics; the plant really draws you in"

A few years ago my interest in medicinal cannabis was piqued after a chat to one of the drug reps. I started reading into the subject, which sucked me down the wormhole, so to speak. I think this is a common experience with most cannabis professionals and interested laypeople. There is such a vast amount of fascinating science around the chemistry, botany, pharmacology and genetics; the plant really draws you in. Not to mention the history, politics and economics related to cannabis. It really is very different from standard therapeutics.

Most of what I have learned has come from working in one of the pioneering specialist clinics. I was lucky to have some involvement in research, and some exposure to really complex cases in conjunction with some amazing experts. I’ve returned back to full time GP work for now. I hope to continue learning in this field. Often we learn the most from our patients.

What conditions can medicinal cannabis be prescribed for?

What are the most common conditions you prescribe medicinal cannabis for?

Without a doubt the most common indication for cannabinoid therapy is chronic pain. This is because chronic pain is unfortunately extremely common, affecting an estimated 3 million Australians. As we all now know, there are very few effective and palatable long term options for sufferers of chronic pain. Doctors and patients are all beginning to turn away from chronic opioid use. We have come to the realisation that they don’t really help, and come with a host of side effects, dangers and dependency issues. Increasingly, doctors and patients are becoming more aware of cannabis based medications as a potential alternative analgesic and are seeking legal access.

person holding neck in pain

Pain is part of the common progression of chronic illnesses of all kinds, including cancer. Other symptoms that invariably come along with chronic disease include insomnia, anxiety, loss of appetite and nausea. Cannabis may have a role in addressing all these symptoms. We hope to enable patients to wind down and de-stress, and achieve a deep, restful, uninterrupted sleep. There is high quality evidence to demonstrate efficacy in the treatment of wasting (cachexia) in AIDS and nausea during chemotherapy (CINV). This may extrapolate to treatment of nausea and appetite in all chronic diseases.

Any other conditions not in your speciality which you are aware of that can be assisted with cannabis?

As General Practitioners we have a working knowledge of all conditions (not including the exceptionally rare). What we are really skilled at is supporting our patients through their illness journey, regardless of the diagnosis. We are exposed to the broadest possible array of conditions, throughout the human lifespan. Cannabis has potential in the symptomatic treatment of a wide array of illnesses. There really shouldn’t be any conditions outside of our speciality as GPs that we can’t treat with cannabis. In other words; GPs are best placed to become cannabis medicine “Specialists.” Especially as cannabis is directed at symptom management (not a cure) and has evidence to support its safety

Cannabis seems to be effective treating:

  • Neuropathic pain

  • Insomnia

  • PTSD

  • Inflammatory bowel issues

  • Inflammatory arthritis

  • Palliative care

  • Nausea Multiple Sclerosis related muscle spasticity

I’ve seen mixed results in:

  • Movement disorders

  • Anxiety

  • Depression

  • Osteoarthritis related pain

Cannabis can be a calmative, and is showing promising results in settling the agitation of dementia and autism.

All of the above conditions and symptoms should be well within the remit of GPs. Outside of this, cannabis has been shown to be an effective adjunct in the treatment of certain resistant paediatric epilepsy subtypes. There is also lots of research ongoing into cannabis as a potential treatment for various cancers, as a neuroprotective agent post head injury, and as an anti-inflammatory in the treatment of COVID-19 related ‘cytokine storm.’ These treatments still seem a long way off, with much more investigation needed.

Can cannabis help with anxiety and depression?

Cannabis may be a calmative and help patients relax, allowing them to quieten negative, persistent and distressing thoughts. This is one way that it may help anxiety. Cannabis can promote restful sleep which can reduce anxiety, improve mood and wellbeing.

sad balloon on ground

Personally I feel cannabis is a depressant, similar to alcohol, in that it damps down the mind’s activity. There is a risk of worsening low mood. Anxiety and panic is also a common side effect of cannabis treatment as patients get used to the effects of THC. Cannabis is certainly not an antidepressant and I don’t personally feel it can be a substitute for antidepressants in depressive disorders.

Depressed mood is another common symptom of chronic illness, as patients face disability and hopelessness. There is invariably an elevation in mood as pain levels decrease, activity levels lift, quality of life improves, and sleep becomes more restful.

Most common side effects of medicinal cannabis?

Some of the side effects of cannabis are somewhat paradoxical in that they are the opposite of the therapeutic effects we are looking for. These can include:

  • Insomnia

  • Racing thoughts

  • Headache

  • Nausea

  • Anxiety

  • Panic

The most common side effects are well known, including:

  • Drowsiness

  • Dry mouth

  • Increased appetite

  • Red eyes

  • Dizziness

  • Euphoria or feeling ‘high’

  • Confusion

  • Memory impairment

Palpitations and racing heart are distressing side effects. I’ve also known patients to have bouts of shivering.

With oils the possibility of overdose is a concern unless the patient is properly educated. This is because it can take two hours or so for swallowed oil to take effect, and there is temptation to repeat the dose. Overdose can cause severe anxiety and panic, rapid heart rate, vomiting and disabling dizziness, possibly with hallucinations. One of the major advantages of cannabis medication is that in overdose there is no danger to life. There is no effect on the breathing and cardiac centre of the brain.

"Each person’s endocannabinoid system is unique, and our reactions to cannabinoids are all very different"

Each person’s endocannabinoid system is unique, and our reactions to cannabinoids are all very different. Some people can be exquisitely sensitive to cannabis and cannot tolerate even low doses. Some patients can have a high tolerance despite having never used the drug. Older people are often more sensitive, but there are no obvious predictors for response. It is likely to be genetic. Note that for some people cannabis just does not work.

In managing the side effects, there is one phrase that always holds true; ‘start low, go slow.’ We should always start at a low dose and very gradually increase as needed and tolerated. Be patient. We need to give our endocannabinoid systems time to adjust and build tolerance to the side effects of cannabis. Generally we can work through the side effects and build up to a dose that is effective in managing the symptoms. Interestingly, there is generally very little tolerance to the beneficial effects of cannabis. However should this occur and the beneficial effects diminish, then a brief cannabis ‘holiday’ can boost the effectiveness again.

Can a patient be prescribed multiple cannabis products at the same time?

Yes. We need to seek approvals separately for each product, but there is no reason not to use several products. A common approach is to use a higher CBD, lower THC product in the day time, and a higher THC product at night.

Oil forms of cannabis can be used for their slow release properties, smoothing out the pain or symptoms. There might be a role for vaped cannabis products as a quick onset ‘as required’ medication, for exacerbations of pain or anxiety.

Can cannabis products interfere with other medications?


Is it safe to use cannabis products whilst I’m still prescribed opioids or other pain medications?

Cannabis is metabolised in the liver. It can increase or decrease the metabolism of a long list of medications. Patients need to seek specific advice on their medications from their doctor, as there is always potential for dangerous reactions.

Generally speaking however, there are very few analgesics that interact with cannabis. Cannabis is always initiated at a very low dose with gradual, incremental increases of dose as tolerated and required. Patients should refrain from immediately ceasing their other medications, and should seek advice on gently weaning their previous medications down as they build their cannabis dose up.

What are the chances of getting THC/CBD oil to help with drug withdrawal symptoms or when I'm on Opioid Substitution Therapy (OST)?

This is a good question. I also have some experience with Opioid Substitution Therapy (OST) in the treatment of Opiate dependence. If a patient has a valid medical reason for a trial of medicinal cannabis there is no scientific argument against combining the two therapies. However, medicinal cannabis is a Schedule 8 medication, unless the THC content is below 0.2mg per ml. This means authority for prescribing must be provided by the state government. The state health department has the responsibility of making public health decisions. In my experience people registered as ‘Drug Dependant Persons’ (a requirement of OST) will not be granted permission for Schedule 8 medicines, as this is one of the risk factors for drug misuse. I expect this will change with time as further evidence emerges regarding the low dependency risk of medicinal cannabis. The risk of harm is certainly lower that of amphetamines and opioids.

Tips for keeping the cost of medicinal cannabis down

Any tips for patients wanting to keep the cost down when medicating with cannabis products?

The best way to keep the costs of medicinal cannabis down is to work closely with an experienced cannabis doctor that is familiar with a broad range of cannabis products. There should be a focus on finding the lowest dose of the correct ratio product that is most effective for you, from the producer that has the lowest cost per milligram high quality product. Note that cannabis medication could and should offer a ‘personalised medicine’ approach.

Why is it so expensive to get cannabis prescribed?

Cannabis clinics have overheads, as do independent GPs to an extent. Clearly there is a supply and demand mismatch that could be exploited. However most of the doctors that are truly passionate about providing widespread access to cannabis treatment still need to charge private fees.

"you are paying for the purity and consistency that black market products cannot achieve"

The reason for this is that there is a fair ‘opportunity cost’ to the doctor as they move into medicinal cannabis from mainstream general practice. In other words, doctors are missing out on a guaranteed income from standard practice when they spend time with cannabis patients.

Regarding the cost of the products, this is set by the producer. It is getting more competitive all the time. Quality control is apparently one of the biggest expenses in medicinal cannabis manufacture, so you are paying for the purity and consistency that black market products cannot achieve.

Why don’t most doctors accept medicinal cannabis as a valid treatment?

One obvious reason is lack of education. During my time at university I didn’t hear the Endocannabinoid System mentioned once. Only recently are we starting to realise the importance of this system as a balancing mechanism in almost every aspect of the body’s function.

I’ve heard several concerns raised by doctors regarding cannabis. One is a worry that we would be replacing one addictive medication (opioids) with another. It is not that long ago that we were assured that slow release Oxycodone, Tramadol and Tapentadol do not cause dependency. I remember a drug company representative telling us just that in an educational meeting during my first year of being a junior doctor. I’ve heard several doctors say they are reluctant to make a similar mistake again. It is likely to take extra effort and research to convince the broader medical fraternity that cannabis is safe and non-addictive at medicinal doses.

Another common concern is that there is a risk to the patients mental health from cannabis. There is likely to be a risk of psychosis and dependence in vulnerable young people smoking large amounts of high THC cannabis (skunk) illicitly. It is uncertain if this extrapolates to typical medicinal doses under supervised treatment. Cannabis has been demonstrated to be an effective treatment for several mental health issues including PTSD. There is very early research ongoing exploring cannabis as a treatment for Schizophrenia symptoms. Clearly the treating doctor needs to carefully assess the mental health risks and closely monitor the patients during treatment, but most common mental health issues should not preclude cannabis treatment.

"without large scale randomised control trials the majority of specialists will always be sceptical"

Cannabis is very different from medications doctors generally prescribe. It is a whole plant extract containing many potentially active ingredients, which likely interact to produce an effect greater than the sum of its parts i.e. the entourage effect. In contrast, conventional medication is generally a single molecule targeting a single receptor for a defined condition. Medicinal cannabis doesn’t lend itself to randomised control trials which is the gold standard level of evidence used to demonstrate effectiveness in conventional medicines. There is plenty of evidence supporting medicinal uses of cannabis, but without large scale randomised control trials the majority of specialists will always be sceptical.

On behalf of the BudHerd team, thank you for taking your time to answer these questions.

It really is my pleasure to chat. I hope you’ll have me again soon.

Dr Stephen Chalk

Dr Stephen Chalk

Dr Stephen Chalk studied medicine in Oxford and Kings College London. He trained in Emergency Medicine at Joondalup, and General Practice in Albany. Steve has been involved in cannabis research and previously worked in one of the pioneering specialist cannabis clinics. He is currently practising as a GP in Perth and enjoys treating minor injuries, lumps and bumps, chronic disease, and men’s health issues.
Jason Lu | BudHerd

Jason Lu | BudHerd

Jason is one of the lead editors and founder of BudHerd. He spends his days writing, designing, developing and researching all things cannabis. Jason is passionate about destigmatising and educating Australians on the therapeutic and recreational values of cannabis.
The statements made on this website are for information and educational purposes. BudHerd and its affiliates are not recommending anyone to use or cultivate cannabis for medicinal or recreational purposes. Please consult with your doctor before using medicinal cannabis to learn about the associated negative side effects. Medicinal cannabis is regulated by the Therapeutic Goods Administration in Australia and more details about cannabis as a scheduled drug can be found on their website.