As research on cannabis emerges, what we know about how it interacts with the liver is becoming more and more complex. As such, here is a brief look at some of the research so far.
In a study of 42 people, researchers investigated how long term chronic cannabis use affects general liver function. Ultimately, they found no significant difference in liver function among those with higher levels of THC markers in their blood. They also found that those with higher THC-OH levels tended to have better liver function. While their sample size was small, the researchers said that their study nevertheless shows that chronic use of medical marijuana does not adversely affect liver health in otherwise healthy individuals.
Researchers have also been investigating the effects of cannabis in those with alcoholic liver disease (ALD), a condition caused by heavy, long term alcohol consumption. As cannabidiol is a known antioxidant, researchers supposed that it might be able to prevent oxidative stress and thus alcohol-induced liver steatosis, or abnormal retention of fats in the liver. While experiments found this to be true in both mice and cell cultures, human studies are still necessary to see how the findings translate over.
However, some cautionary studies on how cannabis interacts with the liver exist too. Research has shown that chronic hepatitis C virus may be made worse by cannabis use. In particular, animal studies have shown that cannabis may worsen liver fibrosis and steatosis in those with hepatitis C. More than this, human studies have shown that cannabis use may suppress anti-viral immunity in those with hepatitis C.
But these findings are not universal. A study from 2018, for example, found that hepatitis C patients who used cannabis tended to have lower levels of cirrhosis (liver scarring) and lower total health costs than non-users.
How cannabis interacts with certain drugs is also interesting to consider. While there are few studies on how cannabis use influences drug mechanisms to do with the liver, cannabis is known to interact with drug-metabolizing enzymes in the liver, which could make certain drugs more or less potent.
To conclude, while cannabis generally seems safe for healthy individuals, those on certain drug regimens and/ or with pre-existing conditions should exercise caution when using the plant as it may exacerbate their health issues.