CBD ‘exceptionally safe’ even at high doses, says study

CBD is ‘remarkably safe’ and well-tolerated even at higher doses, according to a new scientific paper, but there is limited evidence for its efficacy in smaller amounts.

Researchers investigating the safety and efficacy of CBD have concluded that the compound has a ‘remarkably safe profile’ even at higher doses.

They found limited evidence, however, to support its efficacy at doses lower than 400mg, with its potential for treating anxiety showing the most promise. 

While CBD is becoming more widely used and increasingly easy to access across the world, there are still some concerns around its safety, with limited scientific evidence having been conducted on the cannabinoid.

A team of scientists from the Lambert Initiative for Cannabinoid Therapeutics at the University of Sydney have carried out a review of the current scientific literature to evaluate the efficacy and safety of oral CBD products at lower doses (up to 400mg a day). 

This is still significantly higher than the UK guidelines for the maximum daily dosage of CBD, which is currently 70mg.

‘Exceptionally safe’

The team identified a total of 29 double-blind, placebo-controlled trials and six open label studies investigating ‘low’ oral doses of CBD.

Based on their findings they concluded that CBD ‘appears exceptionally safe’ with ‘few concerns’ even at doses of up to 6,000mg (or 1,500mg in multiple doses) – 15 times the maximum dose set for the study.

The authors also note that Epidiolex, which is available on the NHS for certain forms of rare epilepsy, is dosed up to 50 mg/kg/day, equating to 3,000mg per day for a 62kg adult.

They write: “The current review found few concerns around safety across the 45 studies analysed. Where side effects were reported they were typically minor, and often in studies that lacked a placebo control, and therefore could not be unambiguously attributed to CBD itself. 

“Few adverse events were reported in any of the studies considered, even at the 300–400mg dose range where efficacy was most often reported.”

Limited evidence for efficacy at low doses 

However, there was limited high-quality evidence for its efficacy at doses lower than 400mg, with its effects becoming more ‘robust as dosage is increased’.

The review focused on five different conditions in which CBD demonstrated some therapeutic potential, including anxiety, insomnia, addiction-related disorders and chronic pain.

Its efficacy in anxiety shows the most promise according to the paper, but only at doses of 300-400mg and often in studies carried out on ‘healthy’ participants rather than those living with a diagnosed anxiety disorder.

While the authors say it would be ‘premature’ to conclude CBD at doses lower than 400mg did not have anxiolytic effects, higher doses appear ‘more assured of efficacy’. 

Further trials ‘urgently’ needed 

The authors have recommended that further high-quality clinical trials involving lower oral doses of CBD are needed ‘urgently’ in order to clarify its role as a therapeutic.

“The currently sparse evidence base around low doses of CBD may be improved by future clinical trials that better validate efficacy at this dose range,” they write in the paper’s conclusion.

“The current evidence suggests CBD at doses of 300–400 mg has promise, especially as an anxiolytic and anti-addiction agent, and larger randomised, double-blind, placebo-controlled trials are required to reinforce these data.”

They also note that further developments in drug development could lead to improvements in the bioavailability of CBD.

They add: “Given the current intensity of worldwide research activity around CBD, and associated commercial potential, it would appear that advances in our knowledge are just around the corner.”

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