Doc Talk #176 – Medical Marijuana: Miracle or Meltdown?

The legalization of marijuana in Canada has prompted renewed debate about the use of cannabis for treating medical conditions. The use of medical marijuana has tripled every year since 2014, but as Dr Dan and Jamieson discuss in this show, much of this has likely been driven by marketing rather than improved clinical outcomes.

In this show, we talked about medical marijuana and its use in a large number of conditions. In general, the evidence for it having a beneficial effect is lacking. As Jamieson points out, if cannabis is not prescribed by a healthcare provider, then it is not medical marijuana. If you are thinking of asking your doctor about medical marijuana, we’ll provide some guidance and advice about when it might potentially be helpful (and just as importantly when it might not).

The legalization of marijuana in Canada has had an interesting effect on the economics of medical cannabis supply, with a significant increase in price (whilst the cost of illicit marijuana continues to fall).

Image from The Economist

Although marijuana is often posited to have many potential benefits, little is said about the potential harms which can include: unwanted euphoria, sedation, dysphoria, disorientation, low blood pressure, psychosis, and cannabinoid hyperemesis syndrome (cyclic vomiting).

Evidence in clinical trials often has high risk of bias, because typically subjects are recruited who are already current users of marijuana.

The following recommendations for health conditions are taken from the journal ‘Canadian Family Physician’ article “Simplified guidelines for prescribing medical cannabinoids in primary care”.

Health ConditionMedical Marijuana useful?
Acute pain
Rheumatic pain (osteoarthritis, rheumatoid arthritis)
Neuropathic pain
(this is caused by direct damage to nervous system or nerves, this can occur as a result of stroke, multiple sclerosis)
?
(third-line option)
Cancer pain for end-of-life care?
(third-line option)
Nausea and vomiting, general
Nausea and vomiting in pregnancy (morning sickness)✗✗✗
Cannabis use and pregnancy do not mix and have long-term adverse effects on the developing baby
Nausea and vomiting, related to chemotherapy?
(third-line option)
Spasticity
(muscle stifness, eg after a stroke or spinal cord injury)
?
(third-line option)
Epilepsy
Anxiety/depression
(bad idea for mental health conditions in general)

If you are considering the use of marijuana for a medical condition, talk to your healthcare provider about the potential risks and benefits.

(Image by Daniel Oberhaus [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)%5D)

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