Hepatitis C is an infectious disease caused by the hepatitis C virus (HCV) that primarily affects the liver; it is a type of viral hepatitis. During the initial infection period, people often have mild or no symptoms. Early symptoms can include fever, dark urine, abdominal pain, and yellow tinged skin. The virus persists in the liver, becoming chronic, in about 70% of those initially infected. Early on, chronic infection typically has no symptoms. Over many years however, it often leads to liver disease and occasionally cirrhosis. In some cases, those with cirrhosis will develop serious complications such as liver failure, liver cancer, or dilated blood vessels in the esophagus and stomach.

HCV is spread primarily by blood-to-blood contact associated with injection drug use, poorly sterilized medical equipment, needlestick injuries in healthcare, and transfusions. In regions where blood screening has been implemented, the risk of contracting HCV from a transfusion has dropped substantially to less than one per two million. HCV may also be spread from an infected mother to her baby during birth. It is not spread by superficial contact. It is one of five known hepatitis viruses: A, B, C, D, and E.

Diagnosis is by blood testing to look for either antibodies to the virus or viral RNA. In the United States, screening for HCV infection is recommended in all adults age 18 to 79 years old.

There is no vaccine against hepatitis C. Prevention includes harm reduction efforts among people who inject drugs, testing donated blood, and treatment of people with chronic infection. Chronic infection can be cured more than 95% of the time with antiviral medications such as sofosbuvir or simeprevir. Peginterferon and ribavirin were earlier generation treatments that had a cure rate of less than 50% and greater side effects. Getting access to the newer treatments, however, can be expensive. Those who develop cirrhosis or liver cancer may require a liver transplant. Hepatitis C is the leading reason for liver transplantation, though the virus usually recurs after transplantation.

An estimated 58 million people worldwide were infected with hepatitis C in 2019. Approximately 290,000 deaths from the virus, mainly from liver cancer and cirrhosis attributed to hepatitis C, also occurred in 2019. The existence of hepatitis C – originally identifiable only as a type of non-A non-B hepatitis – was suggested in the 1970s and proven in 1989. Hepatitis C infects only humans and chimpanzees.