Original ContributionHematologic Side Effects of Interferon and Ribavirin TherapyKowdley, Kris V MDAuthor Information From the University of Washington, Seattle, WA. Received for publication June 30, 2004; accepted August 25, 2004. Supported in part by NIH Grants 02957 (K.V.K.) and 38215 (University of Washington). Reprints: Kris V. Kowdley, MD, University of Washington, Box 356174, 1959 NE Pacific Street, Room ee-425, Seattle, WA 98195 (e-mail: firstname.lastname@example.org). Journal of Clinical Gastroenterology: January 2005 - Volume 39 - Issue - p S3-S8 doi: 10.1097/01.mcg.0000145494.76305.11 Buy SDC Metrics Abstract Pegylated (PEG)-interferon and ribavirin combination therapy are the standard of care for the treatment of chronic hepatitis C and are associated with a high rate of sustained virologic response. However, there is a high incidence of hematologic side effects with this therapeutic regimen. Hematologic side effects are particularly common; bone marrow suppression caused by interferon may result in neutropenia and thrombocytopenia. Ribavirin is directly toxic to red blood cells and is associated with hemolysis, which is usually dose-related but self-limited. Historically, the traditional management of hematologic side effects of interferon therapy has been dose reduction. However, recent studies have shown that response to therapy is strongly influenced by adherence to optimal doses of interferon and particularly ribavirin. Therefore, there is increasing emphasis on the use of growth factors such as filgrastim and erythropoietin to stimulate bone marrow production of erythrocytes and leukocytes to allow patients to receive the optimal doses of interferon and ribavirin. The incidence, magnitude, and possible mechanisms of hematologic complications associated with interferon and ribavirin are described in this review. © 2005 Lippincott Williams & Wilkins, Inc.