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What Are Inhibitors?
Inhibitors, A to B
Inhibitors might seem mysterious, but understanding them better can help you manage your bleeds and get on with life.
What's an inhibitor, anyway?2
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People with hemophilia A or B can develop inhibitors, which prevent their factor VIII or IX replacement treatment from working to form a clot to stop bleeding.2,3
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People with hemophilia lack certain clotting factor proteins necessary to control bleeds.3
Their treatment contains factor that replaces missing proteins and helps their blood clot.3
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But for some people, the factor treatment may suddenly stop working—and antibodies are to blame.
Antibodies are a part of your body's natural defense system, attacking foreign substances that enter the body. They're valuable for fending off viruses and bacteria.
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For some people with hemophilia, these antibodies view the factor treatment as foreign and attack it, stopping it from working. The antibodies are called inhibitors.
-
People with hemophilia A or B can develop inhibitors, which prevent their factor VIII or IX replacement treatment from working to form a clot to stop bleeding.2,3
-
People with hemophilia lack certain clotting factor proteins necessary to control bleeds.3
Their treatment contains factor that replaces missing proteins and helps their blood clot.3
-
But for some people, the factor treatment may suddenly stop working—and antibodies are to blame.
Antibodies are a part of your body's natural defense system, attacking foreign substances that enter the body. They're valuable for fending off viruses and bacteria.
-
For some people with hemophilia, these antibodies view the factor treatment as foreign and attack it, stopping it from working. The antibodies are called inhibitors.
Inhibitors can happen
Inhibitors usually appear in young children. But they can develop at any age.4 Some people with hemophilia may be more at risk for getting inhibitors than others.
Severe hemophilia A
up to 3 out of every 10 people5
Hemophilia B
up to 1 out of every 20 people5
Who's most at risk for developing inhibitors?
- People with severe hemophilia6
- Children (inhibitors usually develop during childhood)6
- People with a family history of inhibitors6
- African Americans and Hispanics (higher frequency of inhibitors)6,7
Some people with hemophilia A or B may develop inhibitors in response to a treatment that contains factor VIII or factor IX. Most inhibitors appear within the first 150 days of exposure to factor VIII.2,8
We don't know why some people get inhibitors and others don't, but scientists are trying to find out.
Complications: 5 things to know
Severe hemophilia patients with inhibitors don't bleed more often than other severe hemophilia patients. But their bleeds are more difficult to manage because they don't always respond to standard treatment.9
Inhibitor patients may develop serious complications, joint disease, and disabilities.4,10
Moderate and mild hemophilia patients with inhibitors may experience a change in bleeding pattern. They're also at risk for serious complications; many experience severe spontaneous bleeding in joints and muscles.11
Patients with inhibitors are at increased risk for bleeding and are hospitalized more frequently.12
Surgeons may be reluctant to perform surgery or other operations in hemophilia patients with inhibitors if they're concerned about uncontrollable bleeding.13
FEIBA. MADE TO HELP CONTROL BLEEDS AND MANAGE YOUR HEMOPHILIA A OR B WITH INHIBITORS
Inhibitors aren't easy to understand. But they may be manageable.
Want to learn more? Check out our About FEIBA page.
