Hepatitis C is a blood-borne virus. Before routine blood screening for HCV was introduced, the majority of people infected with the virus contracted their infections from tainted blood (e.g. from transfusions). People can also become infected through injection drug use, which at present remains the primary route of transmission.

Hepatitis C is a contagious disease. All individuals infected with hepatitis C are potentially contagions and should be considered as such. Several precautionary measures can prevent the spread of hepatitis C.

The use of shared, unsterilised or inadequately sterilised needles and syringes is the main route of infection in the Western world. Routine blood screening for HCV antibodies was introduced in the early 1990s and has virtually eliminated transmission of the virus through transfusions. By practising good hygiene (e.g. not sharing toothbrushes, razors, etc.), people can reduce the risk of contracting the virus to negligible levels. In about 30% of cases of hepatitis C infection, the route of infection is unknown.