What is hemophilia?

Hemophilia is an inherited disorder in which the blood does not clot normally, causing increased bleeding. It occurs when clotting proteins in the blood are missing or not working properly. Children with hemophilia bleed for a longer time because their blood clots more slowly. Hemophilia can be mild, moderate or severe depending on how much clotting protein is in the blood.


The most common symptom of hemophilia is excessive bleeding. Other symptoms may include:

  • large bruises from small accidents
  • nosebleeds that are difficult to control
  • swelling or pain in the joints or muscles
  • blood in the urine or stool
  • internal bleeding


Hemophilia is diagnosed using blood tests to look at blood clotting and to screen for possible deficiency of different blood clotting proteins. Your child may also have genetic testing to identify the specific mutation responsible for the condition.


Treatment for hemophilia may include factor replacement therapy to replace the missing or low clotting factor or medications to help control bleeding.

Learn more about Pediatric Hematology, Oncology and Stem Cell Transplant services at Boston Children’s Health Physicians.