Inhibitor Basics

An inhibitor is a complication of hemophilia.5

Between 20% and 30% of severe hemophilia A patients and 5% to 10% of patients with mild/moderate hemophilia A develop inhibitors, compared with fewer than 3% of severe hemophilia B patients and fewer than 5% of all hemophilia B patients. Having an inhibitor makes it hard to use factor concentrates for successful treatment.4,5

Most patients who develop an inhibitor do so quickly after beginning treatment with factor concentrates — usually within the first 10-20 days.5

What Is an Inhibitor?

Sometimes the immune system makes a mistake and produces an antibody that destroys natural protectors of the body. Scientists aren't sure why this happens.1

The immune system usually protects our bodies from disease. It produces antibodies — or inhibitors — when it senses a foreign substance in the body. Because the immune system thinks the foreign substance is attacking the body, antibodies are produced to destroy that substance.1,6

When these antibodies attack the clotting factor, the inhibitors neutralize the factor therapy and stop it from working. Since the hemophilia still needs to be treated, other treatment options need to be considered.1,4

The Challenge of Inhibitors

Inhibitors can add frustration and worry to people with hemophilia, as well as their families. This is because inhibitors make bleeds harder to control and treat.6

The good news is that with some planning ahead, finding the right support, and learning more about inhibitors, you and your healthcare team can be prepared to manage inhibitors, prevent bleeds, and treat them quickly when they happen. There are treatment options available, specifically for inhibitors.1,3

KnowInhibitors was designed specifically to help you and your family find some of the knowledge and support you might need. We hope it helps.

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