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Whether you’re taking CBD for joint pain, issues related to anxiety, or insomnia, the effectiveness of your CBD supplement is second only to safety. Scientific reports in the past have suggested that constant CBD use could pose a potential risk to liver health, but further studies and more rigorous scrutiny of the data since then have challenged this statement.
Does CBD cause liver toxicity?
In 2019, a team from the University of Arkansas for Medical Sciences published a study arguing that CBD use had the potential to cause severe liver injury and liver toxicity to people who took it.¹ This stance was widely reported, with the FDA even issuing its own brief statement to manufacturers and consumers about the potential harm that could be caused by taking CBD.
Since the 2019 study, scientists and clinicians have rallied to take a look at the results of this study and others in an effort to understand better what the results from those studies could really mean. They’ve also conducted their own studies based on this body of evidence to shed light on the question of whether liver toxicity is a legitimate concern.
Have studies shown that CBD causes liver toxicity?
Several studies have looked specifically at the effects of CBD products like CBD oil capsules and CBD tincture on the liver, as well as studies with a broader focus on safety and efficacy that included markers of liver health in their evaluations. These studies have included in vitro (cells and tissue samples), animal studies (rodents, dogs, and monkeys), and clinical studies (humans).
An essential principle in answering the question of whether CBD products have been shown to cause liver toxicity in animals and humans is to look closely at the results of each study and the methodologies used to obtain data. These details, while oftentimes overlooked, are the key to truly understanding CBD’s effects on your liver function. The methodology is where you will find the dose, route of administration, and frequency of administration used in the studies, all critical factors in determining both the safety and effectiveness of any compound.
How is liver failure or damage measured?
The liver is an integral component in the body’s metabolizing processes. All the blood which leaves the stomach and intestines passes through the liver, where it can be “filtered” for nutrients. In ideal, healthy conditions, the liver keeps the body in balance, differentiating nutrients from waste, and breaking complex compounds such as drugs down into simpler forms that are either easier for the body to absorb or nontoxic to the body.
The liver is a sophisticated organ, but there are just a few markers that doctors need to rely on when determining whether it is damaged. Enzymes such as ALT and AST are released in greater amounts in response to liver stress, damage, or injury, also referred to as “hepatotoxicity.”² Liver weight is a measure of how much fat is in the liver, and a “fatty liver” points to liver stress or injury. This fatty liver condition is often observed in alcohol-induced liver damage and failure. Elevated liver enzymes or weight are both indicators of increased stress to the liver, but not necessarily of hepatotoxicity, which is more accurately described as one end of a spectrum.
Effects of CBD on the liver
A 1992 study in rhesus monkeys found that rhesus monkeys given 25-50 mg/kg/day of oral CBD every day for three months straight had 13-56% greater liver weights than rhesus monkeys who did not get CBD. This result is alarming, to be sure. But here’s where the principle of scrutinizing how a study was conceived and performed becomes paramount to an accurate understanding of scientific results: this study used individual daily doses that were in excess of 200 mg/kg—that’s nearly 14,000 mg a day for a 150 lb. person! With such astronomically high serving sizes, it’s not surprising that the study subjects demonstrated such overt signs of hepatotoxicity.
Clinical studies aimed at finding a safe and effective anti-epileptic dose of CBD for Dravet’s syndrome and Lennox-Gastaut syndrome patients recommended maximum doses of up to 50 mg/kg. This clinically therapeutic max daily dose of 3400 mg CBD is often many times more than the total amount of CBD included in a whole bottle of CBD soft gels, CBD edibles, or tincture.
Several extensive (involving between 120 and 225 subjects) clinical studies investigating CBD’s effectiveness for seizure disorders (doses ranging between 5-50 mg/kg/day) found that some of the patients taking CBD demonstrated elevated enzyme levels, but not necessarily liver injury.³⁻⁶ Again, this is a significant distinction given that many FDA-approved and safe prescription drugs, as well as alcohol, induce similar elevations in liver enzyme activity. Even the FDA-approved anti-seizure CBD medication Epidiolex® includes mild liver injury as a potential side effect. Overall, the incidence of such occurrences is low, with the safety profile of Epidiolex® far better than those of comparable drugs meant to treat the same disease.⁷
Could CBD actually heal liver injuries?
Remarkably, more recent studies looking at CBD and the liver have suggested that CBD could protect against alcohol-related liver inflammation and injury. These therapeutic benefits are likely related to CBD’s antioxidant properties along with its ability to regulate immune and metabolic processes.⁸ In cellular and animal models of alcohol-induced liver damage and liver disease, the administration of CBD in moderate doses of 5-10 mg/kg significantly reduced levels of oxidative stress, liver enzymes, and fat accumulation.⁹ In contrast to the notion that CBD could be harmful to the liver, this set of studies suggests that even modest doses of daily CBD could reduce the amount of alcohol-related damage incurred by the liver. These results call for further research in humans.
How Do I Take CBD Safely?
The studies reporting that CBD caused liver damage used excessively high servings that are far beyond what is recommended for CBD consumption. Meanwhile, serving sizes that are closer to what is recommended by Lazarus Naturals and other trusted CBD product manufacturers showed highly protective benefits against liver damage.
Don’t be afraid to try a single serving of CBD (usually between 25 and 250 mg) to see if it’s enough to achieve the functional benefits you need. Even higher doses (like 250 mg) only equate to about 4 mg/kg for an average-sized person, which isn’t even close to the clinically safe anti-seizure dose of 50 mg/kg. If you start to notice side effects in addition to the functional benefits, reduce your CBD serving size and get in touch with your healthcare provider.
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Sources:
¹Ewing, L. E., Skinner, C. M., Quick, C. M., Kennon-McGill, S., McGill, M. R., Walker, L. A., ElSohly, M. A., Gurley, B. J., & Koturbash, I. (2019). Hepatotoxicity of a Cannabidiol-Rich Cannabis Extract in the Mouse Model. Molecules (Basel, Switzerland), 24(9), 1694. https://doi.org/10.3390/molecules24091694
²“Liver Function Tests.” Mayo Clinic, Mayo Foundation for Medical Education and Research, 18 Aug. 2021, https://www.mayoclinic.org/tests-procedures/liver-function-tests/about/pac-20394595.
³Devinsky, O., Marsh, E., Friedman, D., Thiele, E., Laux, L., Sullivan, J., Miller, I., Flamini, R., Wilfong, A., Filloux, F., Wong, M., Tilton, N., Bruno, P., Bluvstein, J., Hedlund, J., Kamens, R., Maclean, J., Nangia, S., Singhal, N. S., Wilson, C. A., … Cilio, M. R. (2016). Cannabidiol in patients with treatment-resistant epilepsy: an open-label interventional trial. The Lancet. Neurology, 15(3), 270–278. https://doi.org/10.1016/S1474-4422(15)00379-8
⁴Devinsky, O., Cross, J. H., Laux, L., Marsh, E., Miller, I., Nabbout, R., Scheffer, I. E., Thiele, E. A., Wright, S., & Cannabidiol in Dravet Syndrome Study Group (2017). Trial of Cannabidiol for Drug-Resistant Seizures in the Dravet Syndrome. The New England journal of medicine, 376(21), 2011–2020. https://doi.org/10.1056/NEJMoa1611618
⁵Devinsky, O., Patel, A. D., Thiele, E. A., Wong, M. H., Appleton, R., Harden, C. L., Greenwood, S., Morrison, G., Sommerville, K., & GWPCARE1 Part A Study Group (2018). Randomized, dose-ranging safety trial of cannabidiol in Dravet syndrome. Neurology, 90(14), e1204–e1211. https://doi.org/10.1212/WNL.0000000000005254
⁶Devinsky, O., Patel, A. D., Cross, J. H., Villanueva, V., Wirrell, E. C., Privitera, M., Greenwood, S. M., Roberts, C., Checketts, D., VanLandingham, K. E., Zuberi, S. M., & GWPCARE3 Study Group (2018). Effect of Cannabidiol on Drop Seizures in the Lennox-Gastaut Syndrome. The New England journal of medicine, 378(20), 1888–1897. https://doi.org/10.1056/NEJMoa1714631
⁷Huestis, M. A., Solimini, R., Pichini, S., Pacifici, R., Carlier, J., & Busardò, F. P. (2019). Cannabidiol Adverse Effects and Toxicity. Current neuropharmacology, 17(10), 974–989. https://doi.org/10.2174/1570159X17666190603171901
⁸De Ternay, J., Naassila, M., Nourredine, M., Louvet, A., Bailly, F., Sescousse, G., Maurage, P., Cottencin, O., Carrieri, P. M., & Rolland, B. (2019). Therapeutic Prospects of Cannabidiol for Alcohol Use Disorder and Alcohol-Related Damages on the Liver and the Brain. Frontiers in pharmacology, 10, 627. https://doi.org/10.3389/fphar.2019.00627
⁹Wang, Y., Mukhopadhyay, P., Cao, Z., Wang, H., Feng, D., Haskó, G., Mechoulam, R., Gao, B., & Pacher, P. (2017). Cannabidiol attenuates alcohol-induced liver steatosis, metabolic dysregulation, inflammation and neutrophil-mediated injury. Scientific reports, 7(1), 12064. https://doi.org/10.1038/s41598-017-10924-8