The Science Behind Medical Cannabis

Life on earth relies on plants for sustenance, in the maintenance of health. Without plants, the human race would not have survived as long as it has. The power plants have over other living things, is that plants can make their food. This is known as photosynthesis and is true, so long as they have a source of solar energy, carbon dioxide and water. With a history that dates back thousands of years, the cannabis plant is one of nature’s oldest known medicines. Misunderstood and misrepresented for centuries, the Cannabis plant is being rediscovered globally, in a big way. Clinical studies over the past 20+ years have been accumulated and report evidence of Cannabis and its medicinal prowess. To appreciate the medicinal properties of the cannabis plant, one must take a step back and grasp some basics first.  Learn about the anatomy of the plant, the location of the medical constituents and how they are extracted and prepared pharmaceutically. Understand how Cannabis works within our bodies and the science of the treatment. Prepare to be astounded by the truth about Cannabis.

Why Medical Cannabis?

The cannabinoids found in medicinal cannabis can affect receptors found in most parts of the body, especially in the brain and nervous system. These receptors are part of the endocannabinoid system. This system helps to regulate other systems throughout the body.

When regulation of the endocannabinoid system isn’t working properly, it can contribute to many diseases and conditions including:



Psychiatric Disorders

Neurodegenerative diseases

The two main cannabinoid receptors are called CB1 and CB2 (sometimes referred to as CB1R and CB2R). These  receptors help regulate a range of body functions. CB1 receptors, for example, are found in the Central Nervous System, the Cardiovascular system, Gastrointestinal system, Musculoskeletal system, Immune system, and the Reproductive System.

Therapeutic Uses of Medicinal Cannabis

There are many conditions that your medical practitioner may treat with medicinal cannabis if standard therapies are not working for you. Some of the uses of medicinal cannabis are for:

Chronic non-cancer pain


Symptoms of multiple sclerosis

Nausea and vomiting from chemotherapy

Palliative care

You have been prescribed medicinal cannabis because your medical practitioner has decided medical cannabis is appropriate for your condition and your particular circumstances.

In Australia, medicinal cannabis can only be prescribed by a registered medical practitioner. The rules relating to prescribing medicinal cannabis products can vary between states and territories and may affect whether or not medicinal cannabis can be prescribed.

In New Zealand, all medicinal cannabis products are classified as prescription medicines and from 1 April 2020 can be prescribed by any medical practitioner without Ministerial approval or specialist recommendation.

How should I take my Medicinal Cannabis?

It is important to follow your medical practitioner’s recommendation for the dose of medicinal cannabis for your particular condition. The dose they will recommend can be different for different people and different conditions.

Some things that your medical practitioner will consider are:

The condition being treated

Whether or not you have experience with cannabis

The strength of cannabis products

Whether it will be inhaled or taken orally

Your medical practitioner will recommend slowly increasing the dose of medicinal cannabis until you get the desired effect. Because the levels of THC and CBD are different for different products, the amount that is actually received in the dose depends on the product used. The amount of THC or CBD that your medical practitioner recommends will depend on the condition being treated.

Medicinal Cannabis by Mouth

Medicinal cannabis taken by mouth (orally), as oils or liquid capsules, is absorbed more slowly and has longer-lasting effects than inhaled forms.

The effect of medicinal cannabis taken by mouth is usually seen in 60 – 180 minutes, and the effects usually last for 6 – 8 hours.

Medicinal cannabis oils and capsules come in various strengths and ratios of THC and CBD. Some products are CBD only, others are CBD dominant, some will have a balanced amount of THC and CBD, and others will be predominantly THC. Your medical practitioner will recommend the product that will be most beneficial to you.

Oral Dosing

Medicinal cannabis can be taken orally in the form of oils or liquid capsules. These products are labelled with the amount of THC and CBD per dose. For example, “a blended” 10:10 oil contains 10 mg of THC and 10 mg CBD per mL.

Your medical practitioner will tell you the dose you should start with, and will increase the dose over time until you start to get the desired results.

You may need to wait for at least 60 minutes to see your response to oral medicinal cannabis because of the prolonged onset of action.

Side Effects of Medicinal Cannabis

Like other medicines, medicinal cannabis can cause side effects.

The extent of these side effects can vary with the type and dose of medicinal cannabis product used and can vary for different people. Make sure to let your medical practitioner know if you experience any side effects.

Most people experience less side effects when they “start low, go slow, stay low”, and when they use a product that contains CBD as well as THC.

Adverse events associated with cannabis-based medicines (not comprehensive list of all possible events):

  • Drowsiness/fatigue
  • Dizziness
  • Dry mouth
  • Anxiety
  • Nausea
  • Cognitive effects
  • Euphoria
  • Blurred Vision
  • Headache
  • Orthostatic hypotension
  • Toxic psychosis/paranoia
  • Depression
  • Ataxia/discoordination
  • Tachycardia (after titration)
  • Cannabis hyperemesis
  • Diarrhea

Inhaled Medicinal Cannabis

Inhaled medicinal cannabis is taken in through the lungs by vaporisation. Inhalation is often used when a more rapid effect is required.

The dried flower form of cannabis is used for inhalation.

Smoking cannabis is not a recommended method of ingesting medicinal cannabis. There can be harmful effects in the lungs and some of the cannabis is lost as side stream ‘smoke’ making the dose estimation more difficult.

Vaporisers work by heating medicinal cannabis (without burning it) until the cannabinoids are released and the vapour is then inhaled. Using a vaporiser helps reduce the harmful byproducts and lung symptoms that can occur when medicinal cannabis is smoked.

Inhaled medicinal cannabis acts more quickly than when taken orally. The effects can occur within 90 seconds and reach a maximum after about 15 – 30 minutes and last for 2 – 4 hours.

The actual dose received by inhalation can vary, depending on the type of vaporiser and how you inhale.

Inhaled Dosing

Dried flower cannabis is used for vaporisation. The strength is indicated by the percentage of THC per gram.

Your medical practitioner can help you understand how to use your vaporiser. The following cued puff procedure is recommended with Tilray inhalation products:

  • Recommend use of 190°C vaporisation temperature 
  • When vaporiser is ready, inhale on mouth piece for 5 seconds
  • Hold vapour in lungs for 10 seconds
  • Exhale and wait for 10 – 20 minutes between inhalations to assess effects
  • Recommended maximum of 4 puffs per session

Starting Treatment With Medicinal Cannabis

Access to Medicinal Cannabis

Most medicinal cannabis products are currently unapproved in Australia and New Zealand.

Medicinal cannabis can only be prescribed by a registered medical practitioner after thorough assessment of your condition and circumstances.

In Australia, approval is granted on a case-by-case basis and when your approval finishes or needs to be changed your medical practitioner will need to reapply. You cannot apply or reapply for access to medicinal cannabis products yourself, the request for access must come from your medical practitioner.

In New Zealand, from 1 April 2020, all medical practitioners can prescribe both unapproved and approved medicinal cannabis without Ministerial approval or specialist recommendation.

Support and Further Information

Ask your medical practitioner or pharmacist for a copy of the Consumer Medicine Information (CMI) leaflet for your particular medicinal cannabis medicine. The CMI leaflet will provide you with the important facts you need to know before, during and after taking your medicine.

As with other medications, it is important for medical practitioners to carefully monitor patients using medicinal cannabis. Your medical practitioner may provide you with a symptom diary to fill in and bring back when you next see them. Keeping a symptom diary helps you remember what has happened between appointments and allows your medical practitioner to understand what effects your medicinal cannabis treatment is having.

If you are planning to travel overseas with your medication, check with your medical practitioner, airline or the appropriate government department of the country you are travelling to first to see if there are any legal restrictions – some countries have very strict rules regarding medications being brought into their country. Remember to also ask about any countries you will be travelling through to get to your final destination. In Australia, state and territory governments have specific requirements about prescription and possession of some medicinal cannabis products. These differ between each state and territory, so before travelling interstate with your medication check with your medical practitioner, pharmacist or your local state/territory health department. It is important to stay informed about your condition and its treatment. Talk to your medical practitioner or pharmacist if there is anything you do not understand or are concerned about.

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