The most potent risk factor in the development of hepatitis C is intravenous drug use. Other risk factors include occupational exposure to blood, sexual intercourse with infected individuals, multiple bloods transfusions prior to 1992, and HIV infection.

Percutaneous exposure to blood is the primary mode of HCV transmission. The following are the most important risk factors for HCV infection:^[1][2]:

• Individuals are majorly infected via percutaneous exposure to infected blood. Most persons with HCV were infected.
• Injecting drug use is the most important risk factors nowadays
• Transfusion of blood and blood products, especially before 1992
• Unsafe therapeutic injections, especially in hemophilia patients prior to 1987

Other, less important risk factors include:^[1][2]

• Hemodialysis (Higher rates of infection are observed)
• Solid organ transplantation from infected donors
• Occupational exposure to blood, such as contaminated needle sticks
• Birth to infected mother in cases of detectable maternal HCV PCR at delivery (at the rate of 4%–5%). Breastfeeding is not associated with the transmission.
• Sexual intercourse with infected partner
• Sexual intercourse with multiple partners
• HIV infection
• Tattoo or piercing with infected needle sticks (low risk for transmission after strict infection control measures)