Haemophilia
& Treatment



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This website is intended for carers and patients living with haemophilia.

Haemophilia and Treatment

Inhibitors Explained

People with haemophilia receive treatment (factor replacement therapy) to help their blood to clot. In some people the immune system identifies this factor as “foreign” and starts to produce antibodies against it. These antibodies remove the factor from the circulation, and also block its clotting activity. Because they block or “inhibit” the clotting activity they are known as “inhibitors” and this may mean that factor replacement is no longer effective. Different treatments may then be necessary.

In haemophilia A these antibodies are most often seen early in treatment, in young children. This happens in up to 30% of patients as they begin being treated with factor VIII. In patients with haemophilia B this happens much less often, affecting around 5% of patients.

In some cases the antibody goes away by itself after a while. In others they can last for a lot longer, and may need specialist treatment to get rid of them. In some patients they last for years and can cause significant problems.