Low doses of CBD may harm some people's liver function, study warns
CBD – the non-psychoactive ingredient in cannabis that makes people feel relaxed – has become more widely available in the European Union since the bloc's high court decided in 2020 that it was not a narcotic drug, ruling that CBD 'does not appear to have any psychotropic effect or any harmful effect on human health'.
But the new findings from the US Food and Drug Administration (FDA) suggest that may not be entirely true. In a randomised controlled trial, even small amounts of CBD can affect some people's liver function.
The study included 201 healthy people in the United States, including 151 who used CBD twice per day for four weeks. The CBD doses, totalling five milligrams per day, were within the range of typical consumer products such as edibles, drinks, or lotions.
At the end of four weeks, eight of the CBD users had liver enzyme levels that were more than three times above the normal range – and seven experienced potential drug-induced liver injury.
That's compared with zero among people who did not use CBD.
Elevated liver enzymes, which can also be caused by alcohol, obesity, and some prescription medicines, can be a sign of liver inflammation or damage.
It's not clear why the eight people in the study – 5.6 per cent of those who took CBD – experienced liver problems. They did not have symptoms, and their liver enzyme levels returned to normal within two weeks of stopping CBD.
But the researchers warned that the lack of symptoms could allow liver damage to go undetected, and that people could experience more severe liver issues if they use CBD over longer periods of time or at higher doses.
Notably, there were also no differences between the two groups on endocrine hormones, for example testosterone in men.
While the study was small, it was designed so participants were randomly assigned to either take CBD or a placebo without knowing which group they were in. This kind of trial is considered the gold standard for medical research.
Even so, larger studies with more people would help to confirm the results.
The study authors said more research is needed 'on the long-term effects of CBD use, its impact on various populations, and the safety of lower doses commonly used by consumers'.
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