In the United States, having been born between 1945 and 1965, and use of illicit injection drugs are the two most common factors associated with hepatitis C. Other risk factors include
having received blood transfusions prior to 1990, hemodialysis, and having greater than 10 lifetime sex partners. Population studies show that hepatitis C is more common among males, non-Hispanic blacks, those with low income, and those with less than a high school education.
People who have HIV/AIDS have an increased risk for hepatitis C, because both these diseases are transmitted in the same ways, through blood and body fluids. If a person has both infections, they are said to be co-infected with HIV and HCV.