HoG Handbook

Severity Levels


A person can have mild, moderate, or severe hemophilia.  It depends on how much working clotting factor is in the blood.  This is called the clotting factor level.  It may also be called the level of deficiency or the level of severity.  The clotting factor level is shown as a percentage (%).

The standard factor level is 100%.  You can have a factor level between 50% and 200% and still be considered normal.  In a person with hemophilia, the clotting factor level is much lower than the standard.

Everyone with hemophilia should know their clotting factor level!

This chart shows the three degrees of severity based on the factor level.  It also shows what to expect with each level if there is no treatment.  The kinds of bleeding problems faced by someone with hemophilia usually depend on his clotting factor level. However, some people bleed more and some people bleed less than their factor levels would suggest.  For example, some people with moderate hemophilia bleed just as much as those with severe hemophilia.




Less than 1% factor level
1% to 5% factor level
6% to 50% factor level
Can bleed without injury
Can bleed with slight injury
Can bleed with bad injury, surgery, injections (shots)
May bleed one to two times per week
May bleed one time per month
May only have minor bleeding problems
Usually has joint bleeding
May have joint problems
Rarely has obvious joint bleeding

Severity does not change

Whether a person with hemophilia is mild, moderate, or severe based on factor level does not change.  However, the number and type of bleeds you have might change.  This is because how healthy and active you are can affect your bleeds.  All family members with hemophilia usually have the same clotting factor level.

There is one exception to this. People with a type of factor IX deficiency called hemophilia B Leyden can be moderate to severe at birth but be in the normal range after puberty. Genetic testing is needed to confirm hemophilia B Leyden.