Factor XI Deficiency: Causes, Symptoms, and Treatment
Medically reviewed by Harsha Moole, MD, Internal Medicine. Last reviewed: October 23, 2026.
What kind of doctor treats Factor XI Deficiency?
A hematologist, a doctor who treats blood and bleeding disorders, usually cares for factor XI deficiency. Many are referred to a hemophilia treatment center, a clinic for bleeding disorders. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.
What is factor XI deficiency?
Factor XI deficiency, also called factor 11 deficiency, is a rare genetic bleeding disorder. It is caused by low levels and not enough activity of a blood protein called factor XI. Factor XI is a clotting factor, a protein that helps blood form clots.
People with it do not bleed faster than healthy people. But they may have trouble stopping bleeding from a deep or surgical wound.
It is thought to affect about 1 in 1 million people worldwide. It may be more common than reported, because mild cases often do not get medical attention.
Symptoms
Most people have a mild bleeding tendency. Some have few or no symptoms. How bad symptoms are varies from person to person and is not clearly related to the blood factor XI level.
In most people, long bleeding happens only after surgery, dental work or injury. Possible signs include:
- Bleeding that lasts after an injury or surgery, most often in the mouth, nose or urinary tract.
- Frequent nosebleeds.
- Easy bruising and bleeding gums.
- In women, heavy or long periods and bleeding that lasts after childbirth.
Bleeding into the muscles or joints generally does not occur.
Causes and who gets it
Most cases are caused by changes, called mutations, in the F11 gene. This gene gives instructions for making factor XI.
Severe factor XI deficiency is passed down in an autosomal recessive pattern. This means both copies of the F11 gene have changes. In some families, one changed copy is enough to cause it.
It affects males and females equally.
Some cases are acquired later in life instead of inherited. They can be caused by immune system problems or severe liver disease. The acquired form is not inherited.
How doctors diagnose it
Diagnosis is based on symptoms, your history and family history, and an exam. Blood tests can include a complete blood count and clotting tests.
A clotting test called aPTT is prolonged in factor XI deficiency. But the result can sometimes be normal. A factor XI assay, a blood test, shows low factor XI activity. This test does not predict bleeding risk.
Treatment
Treatment is not always simple, because bleeding is hard to predict. People with it do not need treatment for daily life. They usually need preventive treatment only before some surgeries.
Options include:
- Antifibrinolytics, medicines that help control bleeding, such as aminocaproic acid and tranexamic acid. They work especially well for bleeding from the mouth and for heavy periods.
- Fresh frozen plasma, the liquid part of donated blood, which contains clotting factors. It is the most widely used treatment in the United States. It carries a risk of infection and allergic reaction.
- Factor XI concentrates, which are available in certain European countries but not in the United States. They may be linked to blood clots in some people.
Genetic counseling is advised for affected people and their families.
When to see a doctor
See a doctor if you or your child bleeds for a long time after an injury, dental work or surgery. Frequent nosebleeds and easy bruising are other reasons. Women with long, heavy periods should also be checked.
If you have factor XI deficiency, tell your surgeon or dentist before any procedure.
Call 911 or go to the emergency room for bleeding that will not stop, a head injury, or fainting.
How a direct primary care or concierge doctor fits in
A direct primary care doctor charges a flat monthly fee instead of billing insurance, while a concierge doctor usually charges more and often works alongside insurance. A direct primary care doctor can do a first evaluation and review blood test results. They can also coordinate care with a hematologist or hemophilia treatment center.
Common questions
Is factor XI deficiency the same as hemophilia C?
Yes, factor XI deficiency used to be called hemophilia C. It is not the same as hemophilia A or B. In those types, bleeding into the joints and bleeding with no cause are common. They generally do not occur in factor XI deficiency.
Is factor XI deficiency serious?
It is usually mild. Still, people can bleed for a long time after surgery, dental work or injury. Preventive treatment is usually needed only before some surgeries.
Is factor XI deficiency inherited?
Yes, most cases are inherited. They are caused by mutations in the F11 gene. The severe form needs a changed gene from both parents. The acquired form is not inherited.
Does factor XI deficiency affect women differently?
Yes, in some ways. Women may notice it through heavy periods or bleeding after childbirth. Heavy periods may be treated with birth control pills or antifibrinolytics.
Sources
Medical Disclaimer
This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.
