Cannabis refers to products derived from the cannabis plant, while cannabinoids are the active compounds it contains, including THC, the psychoactive compound responsible for the “high,” and CBD, which does not cause intoxication. Interest in medical cannabis has grown steadily over the past two decades, with claims made about its usefulness for pain, sleep, mood and much more besides. A major review of the clinical evidence, published in JAMA, set out to establish what is actually supported by research and what is not. The findings are considerably narrower than public perception suggests.

What Medical Cannabis Is Approved to Treat

Only three cannabinoid medicines, dronabinol, nabilone and cannabidiol, currently have approval from the US Food and Drug Administration, and that approval covers just three conditions. These are nausea and vomiting caused by chemotherapy, weight loss associated with HIV or AIDS, and rare, severe seizure disorders that begin in childhood, such as Dravet syndrome. For these conditions specifically, the evidence points to small to moderate benefit. Beyond this narrow list, approval simply does not exist.

Where the Evidence for Medical Cannabis Falls Short

Many of the conditions people commonly associate with medical cannabis sit outside what the evidence actually supports. According to the review, cannabis and cannabinoids are not recommended for acute or chronic pain, insomnia, dementia, psychiatric conditions such as post traumatic stress disorder, multiple sclerosis, Parkinson disease, glaucoma, inflammatory bowel disease or rheumatic disease. These happen to be among the most common reasons people use cannabis in practice, which highlights a significant gap between how therapeutic cannabis is perceived and what the science currently shows.

The Risks Behind Therapeutic Cannabis Use

The evidence gap is only part of the picture. Cannabis use disorder, a pattern of problematic use marked by tolerance, withdrawal and harm to work, school and relationships, affects nearly one in three people who use cannabis for medical purposes. This is not a rare or marginal outcome, it is one of the most common consequences of regular use.

Even the approved cannabinoid medicines carry side effects, including dizziness, dry mouth and gastrointestinal symptoms such as diarrhoea. Cannabis obtained outside pharmaceutical channels tends to be considerably more potent, often containing ten per cent THC or more, and can carry contaminants such as mould, pesticides and heavy metals.

Long term or heavy use is associated with further harm, including memory and judgement problems, a raised risk of psychiatric conditions such as psychosis, anxiety and depression, and increased risk of heart disease, stroke and breathing problems including cough, wheeze, asthma and bronchitis. Some people who use cannabis daily and heavily develop cannabinoid hyperemesis syndrome, a condition involving repeated, severe episodes of nausea and vomiting.

Certain groups face particular risk. Cannabis use in children and adolescents is not recommended because of its potential effect on mood and cognitive development, and pregnant individuals are advised to avoid it entirely, since use during pregnancy has been linked to low birth weight infants who are more likely to require neonatal intensive care.

After decades of research and considerable public enthusiasm, the evidence base for medical cannabis remains narrow. It offers real, meaningful benefit for a small number of specific conditions, and for almost everything else, the science has simply not caught up with the claims. Understanding that distinction matters, both for anyone considering cannabis for a health condition and for how it is discussed more widely.

Source: jamanetwork