Hemophilia B FAQs

What is hemophilia B?

Hemophilia B (also known as factor IX deficiency or Christmas disease) is mainly an inherited bleeding disorder caused by a lack of a protein (factor IX) in the blood. This protein is necessary for proper blood clotting.1

How common is hemophilia B?

About 1 in 25,000 males in the United States are born with hemophilia.2 Hemophilia B is the second most common type of hemophilia, making up about 20% of cases.1 Although it is very rare, females can be born with hemophilia if their father has hemophilia and their mother is a carrier.1,3

How do you get hemophilia B?

Most people with hemophilia B have a family history of hemophilia and are born with the condition. However, in about 30% of cases, there is no family history of the disorder and the condition happens as the result of a spontaneous gene mutation.1

What causes hemophilia B?

Hemophilia B is caused by a shortage of a protein in your blood called factor IX, which is essential for normal blood clotting. When a blood vessel is injured, a clot is formed to seal cuts and breaks at the site of injury to stop the bleeding. A person with hemophilia B is unable to form blood clots normally, leading to the prolonged bleeding and easy bruising seen in this disease.1

Who is at risk for hemophilia B?

Hemophilia B is mainly inherited and usually only occurs in males, though in rare cases the disorder can affect females. All races and economic groups are equally likely to be affected.1

What are common symptoms of hemophilia B?

Common symptoms of hemophilia B include3:

  • Bleeding into joints with associated pain and swelling
  • Blood in urine or stool (bowel movements)
  • Bruising
  • Gastrointestinal tract and urinary tract hemorrhage
  • Nosebleeds
  • Prolonged bleeding from cuts, tooth extraction, and surgery
How do I know if I have hemophilia B?

If you are experiencing the symptoms listed in the previous question, and you suspect that you have hemophilia, talk to your healthcare professional. He or she will ask you about your family and personal medical history and will perform a physical examination. Your healthcare professional will also run blood tests to determine whether there is a problem with the level of factor IX in your blood.

How is hemophilia B treated?

Hemophilia B is mainly treated by increasing the level of factor IX in the blood. This can be achieved with replacement therapy, which contains actual proteins to replace the ones that are missing.1

Local clotting agents (antifibrinolytics) are another type of treatment for hemophilia B. They help protect clots and hold them in place and are often used in combination with other medicines.1

What are the different levels of hemophilia B?

There are different levels of severity of hemophilia B—mild, moderate, and severe. It is important to know the level because the proper treatment depends on the severity of the condition.1

Why are males more likely to have hemophilia B than females?

The gene for hemophilia is located on the X chromosomes. Females have (2) X chromosomes, while males have (1) X and (1) Y chromosome. Only the X chromosome carries the genes related to clotting factors.1,3

A male who has the gene for hemophilia B on his X chromosome will have hemophilia. A female must have the gene on both of her X chromosomes to have hemophilia, which is a very rare occurrence.1

Can you get hemophilia B later in life?

Yes, in rare cases, hemophilia can be acquired rather than inherited. This usually happens in older adults and is typically caused by an autoimmune disorder, cancer, or reaction to certain drugs.4

Is hemophilia contagious?

No, hemophilia is not contagious.

What is the difference between hemophilia B and hemophilia A?

Hemophilia A is the result of a deficiency in clotting factor VIII, while hemophilia B is the result of a deficiency in clotting factor IX.5

What are inhibitors?

In rare instances, people with hemophilia B can develop an immune response that triggers the production of antibodies, or inhibitors, to standard factor replacement treatment. Only about 1% to 6% of patients with hemophilia B develop an inhibitor—far fewer than in patients with hemophilia A.6

The risk of inhibitor development is higher if someone in the patient’s family also has an inhibitor, and inhibitors are more frequent among African Americans and Hispanics.7

What is an HTC?

An HTC, or hemophilia treatment center, is a clinic where medical experts and other specialists work together to provide specialized care, education, and support to people with bleeding disorders. The healthcare teams at HTCs include pediatricians, adult and pediatric hematologists (healthcare professionals who specialize in bleeding disorders), nurses, social workers, physical therapists, and dentists.1

There are more than 100 HTCs throughout the United States.

Are support groups available for people with hemophilia B?

Yes, there are support groups available for people with bleeding disorders and their loved ones. Some of the National Hemophilia Foundation’s Chapter Centers offer support groups. You may also find a support group at a hemophilia treatment center (HTC) near you.


  1. Hemophilia B. National Hemophilia Foundation website. https://www.hemophilia.org/Bleeding-Disorders/Types-of-Bleeding-Disorders/Hemophilia-B. Accessed October 21, 2014.
  2. Hemophilia: data and statistics. Centers for Disease Control and Prevention website. http://www.cdc.gov/ncbddd/hemophilia/data.html. Updated August 26, 2014. Accessed October 14, 2014.
  3. Hemophilia B. PubMed Health website. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001566. Updated February 8, 2012. Accessed October 22, 2014.
  4. Giangrande P. Acquired Hemophilia. Revised ed. Montreal, QC: World Federation of Hemophilia; 2012. http://www1.wfh.org/publication/files/pdf-1186.pdf. Accessed October 28, 2014.
  5. Fast facts. National Hemophilia Foundation website. http://www.hemophilia.org/About-Us/Fast-Facts. Accessed October 14, 2014.
  6. DiMichele DM. Inhibitors in Hemophilia: A Primer. 4th ed. Montreal, QC: World Federation of Hemophilia; 2008. http://www1.wfh.org/publication/files/pdf-1122.pdf. Accessed October 22, 2014.
  7. Why some patients develop inhibitors. National Hemophilia Foundation website. https://www.hemophilia.org/Bleeding-Disorders/Inhibitors-Other-Complications/Inhibitors-for-Providers/Why-Some-Patients-Develop-Inhibitors. Accessed October 22, 2014.