In a major study of the impact of cannabis smoking on the progression of liver disease among hepatitis C/HIV coinfected patients, published in July 2013, researchers from McGill University in Canada found no link between cannabis use and liver fibrosis progression in hepatitis C. This result was surprising, since daily cannabis use had previously been associated with the progression of liver fibrosis in this population.85 Earlier studies had shown that cannabis use among patients with the hepatitis C virus resulted in increased liver fibrosis and steatosis.86

The liver disease that accompanies the progression of hepatitis C viral infection typically occurs in a number of stages. The first, steatosis, is an accumulation of fat in the liver and is common in hepatitis C. Fibrosis is the replacement of damaged cells with scar tissue, which interferes with the organization and function of the liver. Steatosis can lead to fibrosis, which can then lead to cirrhosis of the liver, the final stage of liver disease where scarring severely impedes the liver’s function to the point of failure.