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Cannabis doctor consulting patient

As medical cannabis is a highly individualised medicine, there are several variables that doctors need to consider before prescribing this therapy to their eligible patients.

Currently, there are no pre-defined dosage requirements or uniform dosing schedules.

Doctors should advise their patients to ‘start low and go slow’, teaching them to self-titrate until they achieve the desired therapeutic effect.

This blog article covers key information relating to medical cannabis dosing requirements and considerations to help you manage dosing for your eligible patients on medical cannabis treatment plans.

Dosing considerations

Medical cannabis dosing is dependent on a number of factors.

If you’re a medical practitioner considering prescribing medical cannabis to your patient, you must consider the following factors:

  • Patient’s condition
  • Patient’s weight
  • Patient’s age
  • Patient’s metabolism
  • Patient’s endocannabinoid system
  • The type of product that is best suited to their circumstances
  • The consumption method that is best suited to their circumstances

Before prescribing this therapy to your patient, please note that medicinal cannabis may not work for everyone.

As it is not considered a first line therapy for any indication in Australia, medical cannabis should only be considered where conventional treatments have been tried and proven unsuccessful.


How is medical cannabis consumed?

In Australia, there are two primary methods of consumption for medical cannabis. These are inhalation and oral ingestion, both of which have different dosing requirements and effects.

  • Inhalation (rapid absorption) – Inhalation (via vaporisation) is the most common form of administration due to its fast-acting onset. Unlike oral ingestion, the effects of inhalation can usually be felt within 10 minutes and generally last between 2-4 hours.
  • Oral Ingestion (slow absorption) – Oral ingestion (via oil or capsules) is another form of administration that is commonly prescribed in Australia. Although the onset is slower (taking up to 90 minutes) with inhalation, the effects are stronger and last longer, with effects generally lasting between 4-8 hours.

‘Start low, go slow’ – Titration explained

When prescribing medical cannabis therapies to your patients, it is recommended they ‘start low and go slow’. This means patients are required to self-titrate by gradually increasing the dose until the desired effect is achieved.

Titrating is a method used with many other medications which requires the doctor to monitor the patient’s response to identify safe and effective dosing at individualised levels. As cannabis is such a personalised medication, finding the minimum effective dose is key to providing the intended symptom management.

As only patients can truly understand their symptoms and the way they feel, they are ultimately the ones to judge their effective dose.

Read more information on titration here.


What is the biphasic effect?

Cannabis compounds have biphasic properties, meaning that low and high doses of the same substance can produce opposite effects.

Small doses of cannabis tend to stimulate while large doses tend to sedate.

The Biphasic Effect


How do I manage dosing for patients with heart conditions?

For CBD medication, there are usually no contraindications in patients with heart conditions. However, as CBD is metabolised via a major metabolic pathway, it is important to monitor any potential drug interactions.

When considering THC medication for your patient with a heart condition, it’s important to understand that THC can impact the heart’s innervation. This needs to be considered when selecting products and titrating doses for your patient.

If your patient suffers from cardiovascular aliments, it’s important that they discuss their condition with you before proceeding with any treatment plans. By utilising the ‘start low, go slow’ approach, you can monitor your patient’s symptoms and any effects they receive from the cannabis therapy.


How do I manage dosing for patients who are on other medications?

Like with any other prescription medicine, determining exactly what other medications your patient is taking is key before prescribing medicinal cannabis. Once you identify the medications your patient is taking, you can define any potential interactions.

As there are certain medications that can be affected by CBD or THC, the doctor needs to identify the dose, frequency and any potential interactions that may occur, particularly if it’s a CP450 metabolised drug.

In this case, a liver function test may be required at the start of the treatment, as well as at the two and four week mark. Usually the doctor identifies the baseline liver function, followed by initiation and titration of the cannabis therapy. Rising liver function test results can indicate improper metabolism and ultimately, medication interactions.

The bottom line is to start low, go slow and monitor your patient throughout the treatment process.

Patient holding herbal medication

What are the stopping rules for medical cannabis?

Unlike many other medications, patients who are taking medical cannabis can generally stop cold turkey, without experiencing any adverse or undesirable effects.

However, some patients who use THC consistently may experience some minor side effects such as headaches, loss of appetite and nausea.

Medical cannabis therapy should be stopped when:

  • The desired effect is not apparent after 4–12 weeks; and/or
  • Psychoactive or other side-effects are prohibitive (particularly for THC preparations).


How do we know it’s working?

To put it simply, patients taking medical cannabis will experience symptom relief if the therapy is working.

For patients who are uncertain of the efficacy of their treatment plan, it is recommended to cease treatment for 3-7 days to monitor the effects. If their symptoms return, this is an indication that the cannabis medicine may have been working well.

For more information on prescribing medical cannabis therapies for your patient, please visit the TGA website.



The contents in this article donotconstitutelegal advice, arenotintended to be a substitute forlegal adviceand shouldnotbe relied upon as such. You should seeklegal adviceor other professionaladvicein relation to any matters you or your organisation may have.

CanView does not endorse the use of medicinal cannabis without lawful prescription. Just like any medicine, medicinal cannabis may have both positive and negative side effects on the user and should only be prescribed to patients by a health professional with the authority and expertise to do so. The information provided by CanView is for informational and educational purposes and is of a general nature. Patients considering medical cannabis are advised to speak to their general practitioner first to see if it’s a suitable therapy.