Marijuana smoking does not harm the liver; a study of people living with both HIV and Hepatitis C

August 2013


For people living with both HIV and Hepatitis C (HCV), liver disease is a serious concern. Many people living with HIV and HCV also use marijuana either recreationally or to relieve health symptoms. Interestingly, scientific research has shown to be uncertain if smoking marijuana in people living with HIV and HCV is harmful to their liver.



The Canadian Co-Infection Cohort study is a research project involving people living with HIV and HCV from across Canada. As of July 2012, the study included 1118 participants from 17 health care centers in Canada.

The study also collects health information from participants every 6 months, for an average of almost three years. Following people over time makes it possible for researchers to understand whether the cause is associated with the effect.  This is key to understanding the effect of marijuana on the liver. Is it the marijuana smoking that is making the liver worse? Or is it that the liver disease is getting worse, thus causing the patient to smoke marijuana to relieve symptoms?



  • The study included 690 participants; 73% were male, 85% had a low income (less than $24,000/year) and participants averaged 44 years of age
  • Over half the participants said they had smoked marijuana in the past 6 months; 40% of those who said they smoked marijuana said they smoked every day
  • Of 690 participants, 253 developed significant liver fibrosis, a sign of worsening liver disease
  • There was no difference in the progression of liver disease  between the group who smoked marijuana and the group who did not, no matter how much marijuana was smoked
  • The study found no evidence that smoking marijuana leads to quicker liver disease progression



This study shows that marijuana smoking does not increase the progression of liver disease for individuals infected with HIV and HCV.

Further research is needed to better understand the long term used of marijuana on liver disease, as well as the effects of cannabis use that is not smoked (e.g. eaten or in prescription form).


Brunet L et al. Marijuana Smoking Does Not Accelerate Progression of Liver Disease in HIV-Hepatitis C Coinfection: A Longitudinal Cohort Analysis, Clinical Infectious Diseases, 2013.

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