Yes. Many of the direct-acting antivirals (DAAs) used to treat hepatitis C virus carry a black box warning about the risk of hep B reactivation. The two viruses suppress each other, and getting rid of HCV could allow HBV to become active. Anyone who has a current or past HBV infection is at risk. Although serious HBV reactivation is rare, it can potentially lead to liver failure and death.
Despite the potential risk, you can still undergo hep C treatment. However, your medical provider will need to follow certain protocols in order to monitor your safety. According to the HCV Guidelines, people with low or undetectable hep B viral load can either receive preventive treatment for HBV during their DAA treatment, or they can be monitored at regular intervals for HBV reactivation.
Because of the potential seriousness surrounding hep B reactivation, everyone starting DAA treatment for hepatitis C should make sure their provider has tested them for hepatitis B.