Symptoms and Causes of Hemophilia B

Hemophilia B is a rare genetic blood-clotting disorder. Similar to the more common hemophilia A, this condition can cause increased bleeding after even minor injuries and, in more severe cases, extensive, prolonged bleeding that can be life-threatening.

Other symptoms include easy bruising, frequent nosebleeds, and joint pain and swelling. These signs are often seen in childhood, but sometimes symptoms may not develop until adulthood.  

This article will review the symptoms and causes of hemophilia B.

Boy with bleeding wound

Branislav Novak / EyeEm / Getty Images

Frequent Symptoms

Hemophilia B is caused by a genetic defect that results in impaired production of the blood protein factor IX (or factor 9) that plays a role in blood clotting.

Symptoms of hemophilia are largely dependent on the amount of factor IX (FIX) in your blood. Some people may not experience their first episode until adulthood, while others notice symptoms during infancy or childhood.

Early signs of hemophilia B in infancy include:

  • Bleeding into the muscle and deep bruising, sometimes first noticed after a routine vitamin K shot after birth
  • Prolonged bleeding that goes on for a long time after the infant's heel is pricked to draw blood for newborn screening tests
  • Prolonged bleeding after circumcision (surgical removal of foreskin from the penis)
  • Bleeding in the scalp or brain after the use of a vacuum or forceps in delivery, or after a difficult delivery in general

The most common symptom in children and adults is hemarthrosis, which is bleeding that occurs in the joint spaces of the knee, elbow, ankles, shoulders, wrist, and hips. This causes pain and swelling of the joints.

Other general symptoms of hemophilia B that may develop later in life are:

  • Bleeding into a joint or muscle, which causes pain and swelling
  • Bleeding that is not normal after an injury or surgery
  • Easy bruising
  • Frequent nosebleeds
  • Blood in the urine or stool
  • Bleeding after dental work
  • Unexplained bleeding episodes


Bleeding from hemophilia B can affect the internal organs of the body, potentially leading to severe complications and organ damage if left untreated. Organs that may be affected include:

  • Digestive system, causing bleeding in the stool 
  • Kidneys, causing blood in the urine and potentially kidney damage 
  • Lungs, causing hemoptysis (coughing up blood) and difficulty breathing 

If abnormal bleeding develops in the stool, urine, or phlegm, seek out medical care as soon as possible.

Bleeding in the brain (intracranial hemorrhage) is the most immediately life-threatening complication of hemophilia B, occurring in 1%–4% of cases.

This complication is most commonly seen in those with severe cases and may initially present with symptoms of headache, vomiting, neck stiffness, and lethargy. However, it could be silent and only detected through routine imaging. If left untreated, intracranial hemorrhage can lead to chronic neurological disability or even death.

When to See a Healthcare Provider/Go to the Hospital

Recognizing the signs of bleeds in children, navigating school issues, seeking out workplace accommodations, and learning how to manage symptoms of bleeding can be difficult for those with hemophilia B and their families.

Working closely with a healthcare team and knowing the signs and symptoms to look for can hasten your decision-making should an adverse event arise. It can also ultimately help you or your child avoid medical complications.

Some ominous signs of bleeding that you may want to look for are:

  • Spontaneous belly ache that does not go away with eating food
  • Random back or belly pain
  • Swelling of the muscles or joints, especially the elbows, knees, and hips  
  • Unexplained headaches
  • Muscle pain or contractures
  • Any type of bleeding that won’t stop with a normal treatment plan given to you by a healthcare professional 


Hemophilia B is caused by a gene mutation on the F9 gene. If the F9 gene, which contains instructions for creating the blood-clotting protein factor IX, is mutated or defective, it can lead to deficient levels of functional factor IX protein. The bleeding symptoms associated with hemophilia B occur due to this deficiency.

In about 70% of cases, the gene mutation that causes hemophilia B is passed from one's mother. The other 30% of cases arise spontaneously due to a random change in the gene.

In rare cases, it is also possible to develop an acquired form of hemophilia B. This occurs when the body produces antibodies against its own factor IX protein. The reason this happens remains a mystery.


Hemophilia B is an X-linked inherited condition, which means the genetic transmission of the disease is linked to the carrier status of the mother.

The pattern of inheritance, described as X-linked, affects males and females differently because most females have two X chromosomes (XX), and most males have an X chromosome and a Y chromosome (XY):

  • XY males who have the hemophilia B gene mutations will develop clinical effects of the condition because they don’t have another X chromosome that correctly codes for factor IX.
  • XX females who have the hemophilia B gene mutation on one X chromosome are likely to have a healthy version of the gene on their other X chromosome, so they will not have effects of the condition or might have mild symptoms. 
  • XX females who have the hemophilia B-causing gene on both of their X chromosomes will have the condition. This is very rare, as two defective genes would have to be passed on—one from each parent.

Mothers who are carriers have a 50% chance of passing on the hemophilia B gene with each pregnancy. Males who have the condition will pass the mutated gene to all of their female children and none of their male children. This is because males receive a Y chromosome, which does not carry the defective genes that can contribute to hemophilia.

Lifestyle Risk Factors

Most of the time hemophilia B is inherited from a parent, therefore, the main risk factors are factors that can't be changed, such as a family history of bleeding disorders or being male at birth. Still, there are some risk factors that you can change to help mitigate your risk of developing severe medical complications, such as:

  • Avoiding dangerous or risky situations that may lead to injury
  • Avoiding blood thinners, like heparin, Jantoven (warfarin), and Plavix (clopidogrel); and medications that worsen bleeding, such as aspirin or Advil and Motrin (ibuprofen)
  • Practicing good dental hygiene
  • Engaging in routine exercise like swimming and biking, while avoiding contact sports like football and rugby
  • Getting vaccinated—and with the smallest needle possible—to protect you from infections


Hemophilia B is a rare blood-clotting disorder that is often passed down through families. Symptoms include excessive bleeding or bruising even from minor injuries, bleeding from the gums or nose, and aching or swelling in the joints. Bleeding episodes and symptoms can range in severity from mild to life-threatening.

It's important to seek medical care if you have any unusual symptoms or prolonged bleeding. Hemophilia B can affect the internal organs and brain, and if bleeding is left untreated, it can lead to complications and organ damage.

If you have hemophilia B, you may have inherited the gene mutation from one of your biological parents, and your children can inherit it from you. Genetic testing can offer insight into whether you are a carrier.

A Word From Verywell

If you have hemophilia B, it is not uncommon to experience a range of symptoms. Some people may go through long periods of time without symptoms, while others may have abnormal bleeding inside their body for no clear reason.

If you or your child is diagnosed with hemophilia B, lifestyle modifications like exercising regularly and avoiding situations that are prone to causing injuries can help reduce the risk of having a bleeding event. This requires that you work closely with your healthcare team so you can learn how to exercise safely, what medications are safe to take, and how to manage symptoms should they arise. 

It is important to remember that even if you are doing everything right, you can still experience a bleeding event, and that an episode is not a negative reflection of you. If you experience swelling in your joints, muscle pain, unexplained headaches or fever, or spontaneous bleeding episodes, call your healthcare provider or seek immediate medical attention.

4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Hemophilia Foundation. What is Hemophilia B.

  2. Stanford Health Care. Hemophilia symptoms.

  3. Hegde A, Nair R, Upadhyaya S. Spontaneous intracerebral hemorrhage in hemophiliacs-A treatment dilemmaInt J Surg Case Rep. 2016;29:17-19. doi:10.1016/j.ijscr.2016.10.046

  4. Krishnamurthy P, Hawche C, Evans G, Winter M. A rare case of an acquired inhibitor to factor IXHaemophilia. 2011;17(4):712-713. doi:10.1111/j.1365-2516.2010.02457.x

By Shamard Charles, MD, MPH
Shamard Charles, MD, MPH is a public health physician and journalist. He has held positions with major news networks like NBC reporting on health policy, public health initiatives, diversity in medicine, and new developments in health care research and medical treatments.