Infectious complications are associated with the human origin of certain blood products used in the treatment of haemophilia A: in the past, viral transmission (HIV, hepatitis B and C) was a major complication of haemophilia A therapy, but since the introduction of effective viral inactivation processes towards the end of the 1980s, this risk has become minimal.
Immunological complications are due to immunisation of patients undergoing treatment with factor VIII concentrates. The resulting antibodies neutralise factor VIII and render it ineffective within minutes. In one third of patients, these antibodies are transient and disappear within several days to weeks, whereas in others they subsist at varying levels. The presence of antibodies directed against factor VIII may require the use of alternative therapeutic solutions.
Osteoarticular complications result from the high frequency of haemarthrosis and cause gradual loss of function as well as mechanical and inflammatory pain. Such lesions can occur very early and may be seen in children.