UPDATE: See our more recent critique of this publication.
One of the only established harmful effects of CBD is the modulation of liver enzymes. High doses of CBD — a few hundred or thousand milligrams taken orally — can inhibit drug-metabolizing enzymes. Additionally, the elevation of aminotransferases (ALT and AST) is sometimes observed in patients taking CBD and valproate, an anti-epileptic drug. When these enzymes increase, it is usually indicative of ongoing stress on the liver and potential liver damage. Although these changes appear to reverse with cessation of CBD treatment, it is important to be cognizant of the possible reaction. But these problems are seen when 20-50 mg/kg of CBD are given along with other drugs. These concerns are part of the reason that the maximum recommended dose of Epidiolex is 20 mg/kg/day in humans with healthy livers. A recent study took this well out of proportion. University of Arkansas researchers found liver harms when forcing feeding mice up to 2460 mg/kg CBD in one go (123 times the maximal recommended dose; nearly 0.25% of their body weight in pure CBD), or 615 mg/kg over 10 days. The authors propose this as evidence that CBD — at normal human doses — is hepatotoxic, and that this “raises serious concerns about … the safety of CBD.” The work that physicians have done with Epidiolex has provided important insights into legitimate worries about using isolate CBD in certain patients. But warning about the dangers of drinking over 10 bottles of Epidiolex at once adds nothing useful to the discussion.