Hemophilia A FAQs

What is hemophilia A?

Hemophilia A (also known as factor VIII deficiency or classic hemophilia) is an inherited bleeding disorder caused by a lack of a protein in the blood called factor VIII. This protein is necessary for proper blood clotting.1

How many people have hemophilia A?

About 1 in 6,250 males in the United States are born with hemophilia.2 Hemophilia A is the most common type of hemophilia, making up about 80% of cases.3 Although it is rare in females, a girl can be born with hemophilia if her father has hemophilia and her mother is a carrier.1

How do you get hemophilia A?

Most people with hemophilia A have a family history and are born with the condition. However, in about one-third of cases, there is no family history of the disorder and the condition occurs because of a spontaneous gene mutation.1

What causes hemophilia A?

Hemophilia A is caused by a shortage of a certain protein in blood called factor VIII, 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 A is unable to form blood clots normally, leading to the prolonged bleeding and easy bruising seen in this disease.3

Who is at risk for hemophilia A?

Hemophilia A is mainly inherited and usually occurs in males, though in rare cases the disease also can affect females.1 It is equally likely to affect people of all races and ethnic groups.1

What are the symptoms of hemophilia A?

Common symptoms of hemophilia A include4:

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

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 personal and family medical history and will perform a physical examination. Your healthcare professional will also run tests to determine the levels of factor VIII in your blood.

How is hemophilia A treated?

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

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

Speak with your healthcare professional regarding what treatment options are best for you.

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

The genes for hemophilia are located on the X chromosome. Females have (2) X chromosomes, while males have (1) X and (1) Y chromosome. Only the X chromosome carries the genes for hemophilia.4

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

Can you get hemophilia A later in life?

Yes, in rare cases, hemophilia can be acquired rather than inherited. This usually happens in older adults and may be caused by an autoimmune disorder, cancer, or a reaction to certain drugs.5

Is hemophilia contagious?

No, hemophilia is not contagious.

What is the difference between hemophilia A and hemophilia B?

Hemophilia A is caused by a deficiency in clotting factor VIII, while hemophilia B is caused by a deficiency in clotting factor IX.

What are inhibitors?
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 blood 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 A?

Yes, a number of support groups are available to 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 A. National Hemophilia Foundation website. http://www.hemophilia.org/Bleeding-Disorders/Types-of-Bleeding-Disorders/Hemophilia-A. Accessed October 14, 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. Frequently asked questions about hemophilia. National Hemophilia Foundation website. http://www.hemophilia.org/walk/docs/NHFFAQs.pdf. Accessed October 14, 2014.
  4. Hemophilia A. PubMed Health website. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001565. Updated February 24, 2014. Accessed October 22, 2014.
  5. 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.