Chronic hepatitis C progresses slowly over 10 to 30 years. It causes inflammation and scarring of the liver and, if untreated, can lead to liver failure and liver cancer. Treatment clears HCV from the blood and prevents further liver damage. Doctors treat chronic hepatitis C with powerful antiviral drugs that have many side effects. Recently, they found that combining a long-acting immunity-boosting protein (pegylated interferon) with another antiviral drug (ribavirin) was very effective in ridding the body of HCV. However, they did not determine the optimal duration or dose of this therapy.