Harmless, harmful or medicinal


Marijuana advocates argue that the drug can be used to alleviate everything from the pain of rheumatoid arthritis to the nausea caused by cancer treatment. Here’s what some of the research says:

• Two cannabinoid drugs – dronabinol and nabilone – have been approved by the Food and Drug Administration (FDA) in the United States for the treatment of chemotherapy-related nausea and vomiting in patients who have not responded to standard therapy, and they have been shown to be as effective or more effective than other FDA-approved drugs.

• The American College of Physicians has stated that many studies show tetrahydrocannabinol (THC), the principal psychoactive ingredient in cannabis, to be helpful in stimulating appetite in people with severe weight loss because of HIV.

• A 2006 study out of the prestigious Scripps Research Institute showed marijuana can slow the progression of Alzheimer’s disease by blocking an enzyme that causes its progression.

• In 2013 an oncologist at St George’s University of London showed some kinds of non-psychoactive cannabinoids had an inhibitive effect in leukaemia cells. Similarly, a study at the California Pacific Medical Centre in San Francisco found a marijuana compound effective in halting metastasis in some kinds of aggressive cancer.

• A paper in the Planta Medica Journal, a leading publication on medicinal plants, noted the effects of marijuana in anti-inflammatory pain relief in illnesses such as multiple sclerosis and rheumatoid arthritis were several hundred times more powerful than aspirin.

• A 2005 study by scientists at the University of Southern California and the University at Albany, State University of New York, found occasional users of cannabis had lower levels of depressive symptoms such as anxiety and symptoms of ADHD.

• Studies in the late 1970s supported by the US’s National Eye Institute noted that marijuana can help to prevent blindness for those who suffer from glaucoma by decreasing the pressure inside the eye.


Those against the medicinal use of cannabis argue that sufficient evidence that cannabis works as a medicine is lacking – and that the plant is downright dangerous.

• A 2014 study in the New England Journal of Medicine decries the notion that marijuana is not addictive. The study claims that 9% of the people who try marijuana become addicted to it and that the figure doubles when initiation occurs during adolescence.

• The European Respiratory Journal published a study that found marijuana smoking is more harmful than tobacco smoking. Researchers said cannabis smokers end up with five times more carbon monoxide in their bloodstream than tobacco smokers because there are up to twice the levels of carcinogens present in the smoke to begin with, which is compounded because it is often smoked without a filter.

• Vaporisers and nasal sprays are considered a healthier option than smoking. But the concern with vaporisers – which work like e-cigarettes – is that the concentrate used has extremely high levels of THC. That’s why the US’s National Organisation to Reform Marijuana Laws, a nonprofit lobbying group, is calling for regulation of vaporiser pens and inhalers.

• Last month legislators in Colorado in the US, where the drug has been legalised, rushed to impose clearer labelling standards and limits on how much marijuana food can contain after a 19-year-old jumped to his death from a hotel balcony in Denver after eating six times the recommended dosage, and another man allegedly shot and killed his wife after consuming marijuana-laced candy and prescription medication.

• Locally, a Medical Research Council study has suggested a correlation between the use of cannabis and the need for trauma unit care. Researchers found cannabis in 58% of Cape Town-based patients, 29% of Port Elizabeth patients and 44% of Durban-based patients who ended up in trauma units.

• The Lancet medical journal published findings linking marijuana use to higher than normal rates of psychotic conditions such as schizophrenia.

• A Northwestern University and Harvard University study suggests that even casual use of marijuana results in changes in the parts of the brain associated with motivation and addiction, and that the degree of alteration correlated with how much marijuana the subjects used.

Eamon Allan is a freelance writer based in Johannesburg. Follow him on @eamonallan

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