Interferon therapy for chronic hepatitis C is not a cure, but it is able to decrease the viral load and may decrease the risk of complications (e.g., cirrhosis, liver failure, liver cancer). Pegylation of the interferon increases the amount of time the interferon remains in the body by increasing the size of the interferon molecule. Increasing molecule size slows the absorption, prolongs the half-life, and decreases the rate of interferon clearance. Thus the duration of biological activity is increased with pegylated interferon over nonpegylated interferon. The peginterferon alfa products offer an advantage over nonpegylated interferon alfa products because of less frequent administration. Tolerability of the pegylated interferons is comparable to the nonpegylated formulations. Monotherapy with these agents produces a better response in some patients than monotherapy with the nonpegylated formulation. Combination therapy with ribavirin is more effective than monotherapy. Studies comparing peginterferon alfa-2b and peginterferon alfa-2a in the treatment of chronic hepatitis C have not been performed.