A recent Health Canada safety review found that patients infected with both hepatitis B and hepatitis C viruses who are being treated for hepatitis C with direct-acting antivirals may experience a reactivation of their hepatitis B. Hepatitis B reactivation is the return of an active hepatitis B infection, which can lead to serious complications such as liver failure.

As a result, Health Canada is working with manufacturers to strengthen the prescribing information for these drugs with a new warning about this risk.Direct-acting antivirals are prescription medicines used to treat and, in most cases, cure chronic hepatitis C virus infections in adults. Without treatment, chronic hepatitis C virus infections can lead to serious liver problems, including cirrhosis (liver scarring), liver cancer and death.

When Health Canada completed its safety review in October 2016 there were no Canadian cases of hepatitis B reactivation. However, 13 international cases were identified. In some cases, the symptoms reported were consistent with moderate to severe hepatitis B reactivation, with one case resulting in liver failure requiring a liver transplant.