What is hemophilia?

Hemophilia is an inherited bleeding disorder. People with hemophilia bleed easily because they don’t have enough of one of the clotting factors in their blood. Clotting factors are needed for blood to clot. Blood clots to prevent excessive bleeding.

There are many blood clotting factors involved in the forming of clots to stop bleeding. The 2 most common clotting factors affected by hemophilia are factor VIII and factor IX.

How severe the hemophilia is depends on the level of blood clotting factors in your blood. The more severe the hemophilia, the less clotting factor is present. The result is higher bleeding risk or more severe hemophilia.

The 3 main forms of hemophilia include:

  • Hemophilia A. This is caused by a lack of or low levels of the blood clotting factor VIII. It is the most common type of hemophilia. About 9 out of 10 people with hemophilia have type A disease. This is also referred to as classic hemophilia or factor VIII deficiency.
  • Hemophilia B. This is caused by a deficiency of or low levels of blood clotting factor IX. This is also called Christmas disease or factor IX deficiency.
  • Hemophilia C. Some healthcare providers use this term to refer to a lack of clotting factor XI. It is a rare condition.