Hemophilia B

Written by Mary Jo DiLonardo
Medically Reviewed by Brunilda Nazario, MD on September 24, 2025
5 min read

If your child has hemophilia, their blood doesn't clot the way it should. If they have a cut, scrape, or other injury, they will bleed longer than other people do. The bleeding can happen on the surface or inside their body.

It can be serious. With the right treatment, though, and by avoiding certain risks, your child can have an active life.

People with hemophilia don't have enough of a protein that helps blood clot. There are two main types of the condition: A and B. Your child's type depends on which protein, or clotting factor, they lack.

There are 13 of these clotting factors in our blood. With hemophilia B, you don't have enough factor IX. Depending on how severe the lack of clotting factor is, the diagnosis can come as early as childhood. Mild disease can be diagnosed later in life. Only about 2 in 10 people who have hemophilia have this type. It happens more in boys than girls.

Most people inherit it from their mother, who carries a faulty gene.

The main symptoms are bleeding for longer than normal, bleeding and potential damage to joints, and bruising easily.

Depending on how severe their condition is, your child may have:

  • Nosebleeds for no apparent reason
  • Blood loss from small cuts
  • Prolonged bleeding in the mouth from biting down, or after a tooth is removed
  • Bleeding from a cut or injury that starts up again after stopping
  • Unexplained blood in their pee or stool
  • Deep bruises, especially in their muscles

If your child has a muscle or joint that is bleeding, it can hurt, especially when they move it. Usually it's swollen and inflamed.

With this disease, even a small bump to the head can lead to serious consequences. If it happens, get emergency medical help for any of these signs of bleeding in the brain:

In the first six months of life, babies don't fall or get hurt often, so an early diagnosis is rare. But with a severe or moderate deficiency, you may notice issues once your baby becomes more active. As they begin to crawl, they may get bumps and raised bruises. There may be bleeding in the joints. Bruising and long-lasting bleeding from even small injuries may cause a doctor to suspect hemophilia.

The doctor may ask:

  • What happened to cause your child's bumps, bruises, or bleeding?
  • How long did the bleeding last?
  • Are they taking any medication?
  • Do they have any other medical concerns?

Your doctor will also ask about your family's medical history to find out if anyone had a problem with bleeding or blood clotting.

To get the diagnosis, doctors will test your child's blood to find out how long it takes to clot and to see if it's missing any clotting factors. This often includes:

  • Complete blood count (CBC). It gives important information about the kinds and numbers of cells in your blood.
  • Prothrombin time (PT) and activated partial thromboplastin time (PTT). Both test how long it takes blood to clot.
  • Factor VIII and factor IX tests. These measure levels of those clotting factors.
  • Possible molecular genetic testing

If your child is diagnosed with hemophilia B, you'll probably have a lot of questions. You might want to ask your doctor:

  • Is this a severe case?
  • Have you treated someone with this condition before?
  • What treatment do you recommend?
  • How often will we need to come to the doctor's office?
  • How long is too long to bleed from a small cut?
  • What do we need to look out for? Are some symptoms more serious than others?
  • Are there over-the-counter medicines we should or shouldn't use?
  • How do we keep safe? Do we need to limit activities?
  • Do we need to make teachers and care providers aware?
  • How do we connect with other families who have kids with hemophilia?
  • What are the chances our other children will have hemophilia? What about our grandchildren?

There is no cure, but you can manage the condition, and your child can enjoy an active life. They can get the factor IX their body doesn't make if they have severe deficiency or if they have frequent bleeding. This is called replacement therapy. With this treatment, doctors use a needle to put clotting factor IX into the bloodstream. The replacement protein can come from human blood, or it's made in a lab.

If your child has severe hemophilia, they may need regular treatments to prevent bleeding. If they don't, they may need only treatment to stop bleeding after it starts.

You can get replacement therapy at a clinic or from a visiting nurse, or you can learn to do it at home. There are newer treatments that include helping your body create more clotting factors, preventing clots from breaking down, and applying sealants directly to wound sites to promote clotting and healing

Other treatments, approved for ages 12 and older, include:

For adults with factor IX levels of 2% or lower, there's also gene therapy for hemophilia B.

Besides giving any factor replacement that may be needed, quick first aid is important when your child gets hurt. Clean any small cuts, scrapes, and injuries, and apply pressure and a bandage right away. Serious injuries need medical attention.

Exercise and keeping a healthy weight are important, too. Working out helps strengthen muscles, which can lessen bleeding from injuries. Extra weight puts more strain on the body, and that can increase problems from bleeding. Avoid high-risk activities that may lead to head injuries. 

Make sure all your health care providers are aware of your child's condition. They may need to take medications to help clot their blood before certain procedures, like dental work.

Some over-the-counter medications, like ibuprofen, or herbal remedies can cause bleeding, so check with your doctor before giving them to your child.

Try to avoid injuries. Make sure your child wears knee pads, elbow pads, and a helmet while playing. Use safety straps in car seats, strollers, and high chairs. Check your home and yard for possible problems like sharp edges.

With the right precautions and planning, your child can keep doing all the things they love to do.

See the doctor regularly, and make sure to follow the treatment plan.

For more information about hemophilia B, visit the website of the National Bleeding Disorders Foundation.