Hemophilia is a rare bleeding disorder characterized by low levels of proteins called “clotting factors.”

Hemophilia is an inherited blood disorder in which your blood does not clot properly. This can cause you to bleed more easily and sometimes lead to excessive bleeding, even from minor cuts or injuries.

There are several types of hemophilia, which are characterized by low levels of certain clotting factors. Healthcare professionals base the overall severity of the condition on the amount of factors present in the blood.

The exact number of people living with hemophilia is not known, but it affects more people assigned male at birth than those assigned female.

According to the Centers for Disease Control and Prevention (CDC), around 33,000 males in the United States have hemophilia.

Keep reading to learn more about the types, symptoms, causes, and treatments of hemophilia.

There are three types of hemophilia, including hemophilia A, B, and C. These are caused by a protein deficiency in the clotting factors 8 (factor VIII), 9 (factor IX), and 11 (factor XI).

  • Hemophilia A: Type A is the most common type of hemophilia. A deficiency in factor 8 causes this form of hemophilia, which is also known as “classic hemophilia.“
  • Hemophilia B: This type of hemophilia, also known as Christmas disease, occurs because clotting factor 9 is missing or severely deficient.
  • Hemophilia C: Hemophilia C, also known as “factor XI [11] deficiency,“ is a rare form of hemophilia first discovered in 1953 in people with severe bleeding after dental extractions.

Hemophilia is an inherited genetic condition. There is no cure for hemophilia, but treatment could help you manage symptoms and prevent future health complications.

The symptoms of hemophilia may vary based on the severity of the condition.

In mild cases of hemophilia, you may only experience excessive bleeding after experiencing trauma, such as tooth extraction, vaccinations, surgery, or injury.

In more severe cases, you may experience the following symptoms:

  • frequent, difficult-to-stop nosebleeds
  • bruising, bleeding into the skin
  • blood in stool or urine
  • bleeding in gums or mouth
  • bleeding into the joints
  • bleeding into the muscle and soft tissue
  • hemorrhaging following childbirth

Symptoms of mild hemophilia usually only occur after an incident, so doctors may not diagnose it until you reach adulthood. In more severe cases, a doctor may diagnose the condition following a circumcision shortly after birth.

Hemophilia C is generally considered to be a mild form of hemophilia, which means its symptoms and signs align with those of mild cases of A or B.

The primary cause of hemophilia is a mutation in the genes that control and regulate the development of clotting factors. This is called congenital, which means you acquire the trait from one or both of your parents at birth.

About two-thirds of type A and B cases of hemophilia occur in people with a family history of the condition.

It’s also possible to develop acquired hemophilia with no personal or family history of hemophilia. This is known as acquired hemophilia, which is a rare autoimmune disorder.

An autoimmune disorder occurs when your immune system attacks healthy cells. In acquired hemophilia, the immune system creates antibodies that attack the clotting factors, most frequently factor 8 (acquired hemophilia A).

Genetics play a role in all three types of hemophilia.

Both hemophilia A and hemophilia B involve a recessive mutation on the X chromosome. Biological males typically have an X and Y chromosome, while biological females typically have two X chromosomes.

This means biological females are less likely to inherit hemophilia since they almost always have at least one non-mutated X chromosome. Instead, they can become carriers if they acquire one copy of the mutated X chromosome.

Being a carrier means that the person will not show any signs or symptoms of the condition, but they can still pass it on to their children. For example, biological males can inherit hemophilia if their mother is a carrier and they get the mutated X gene from them.

Hemophilia C is an autosomal inherited form of the disease. It affects biological males and females equally because the genetic defect that causes this type of hemophilia isn’t related to sex chromosomes.

In the United States, hemophilia C affects about 1 in 100,000 people.

A doctor can diagnose hemophilia by examining your family and medical history and through a blood test.

A doctor will remove a small sample of blood from your vein and measure the amount of clotting factor present. The sample is then graded to determine the severity of the factor deficiency and the severity of the condition.

Hemophilia A severity levels include:

  • Mild: factor levels are between 6% and 30% (about 25% of all cases)
  • Moderate: factor levels are between 1% and 5% (about 15% of all cases)
  • Severe: factor levels are less than 1% (about 60% of all cases)

Hemophilia B severity levels include:

  • Mild: factor levels are between 6% and 49%
  • Moderate: factor levels are between 1% and 5%
  • Severe: factor levels are less than 1%

Treatment for hemophilia can vary based on the type of hemophilia you have. The main goal of treatment is to replace the clotting factors so a person can form clots and prevent bleeding.

A doctor may prescribe the following based on the type of hemophilia you have:

  • Concentrated FVIII or FIX product: Often called factor replacement therapy, these infused medications are used to treat types A and B, respectively. The medication can either be synthetic or made from human plasma. Often doctors prescribe them as part of an ongoing, regular treatment regimen known as prophylaxis.
  • Aminocaproic acid: This medication helps prevent the breakdown of blood clots. Doctors may prescribe this medication prior to a dental or other procedure.
  • Non-factor replacement therapies: These medications are a newer form of therapy that uses synthetic proteins to replicate the clotting factors. A doctor injects the medication into the skin. Examples of this therapy include emicizumab and desmopressin acetate.
  • Gene therapies: In 2023, the Food and Drug Administration (FDA) approved Roctavian, a gene therapy to treat severe hemophilia A in adults.
  • Other therapies: The FDA approved marstacimab-hncq (Hympavzi) in 2024 to prevent or reduce bleeding episodes in people ages 12 years and older with hemophilia A.
  • Physical therapy: In more severe cases, you may require physical therapy for rehabilitation if hemophilia has damaged your joints.
  • Pain management: If you have pain associated with the condition, a doctor may prescribe or recommend pain medications to help alleviate the pain.

Hemophilia is a condition that’s typically passed from parent to child. When someone is pregnant, there’s no way of knowing whether the baby has the condition.

However, if your eggs are fertilized in a clinic using in vitro fertilization, they can be tested for the condition. Then, only the eggs without hemophilia can be implanted.

If you’re worried your baby may develop hemophilia, preconception and prenatal counseling could help you understand your risk of passing hemophilia on to your baby.

Complications of hemophilia can include:

  • joint bleeding, inflammation, and damage
  • neurodegenerative problems in the knees, ankles, elbows, or wrists
  • pseudotumors, which may affect tissues near long bones or the pelvis
  • deep internal bleeding
  • bone fractures
  • neurological symptoms from bleeding within the brain
  • coma

You’re also at an increased risk of developing infections, such as hepatitis, when you receive donor blood.

The most common complication of clotting factor treatment is the development of inhibitors, which are antibodies that can make treatment less effective.

It’s important to get immediate medical attention if you experience any of the following symptoms, especially if you’re pregnant:

  • severe headache
  • vomiting repeatedly
  • neck pain
  • blurred or double vision
  • extreme sleepiness
  • continuous bleeding from an injury

With proper treatment, many people with hemophilia can live almost as long as people without the condition. However, hemophilia life expectancy may differ based on treatments and disease severity.

Though treatment can help improve and prevent symptoms, there is currently no cure for hemophilia. You will need regular treatment to ensure your blood clots normally.

The most common treatment for hemophilia is clotting factor injections to help increase the levels in your blood. Other treatments may include monoclonal antibodies, non-factor replacement therapies, and gene therapies.

Hemophilia is a blood condition associated with heavy bleeding. There are three types of hemophilia: A, B, and C. They differ in what clotting factors are affected.

The severity level of hemophilia can affect symptoms and their severity.

Treatment focuses on replacing clotting factors to prevent future issues with bleeding. A doctor may also recommend additional therapies as needed.