Hearing the word “severe” to describe your or your child’s hemophilia can sound alarming. You may wonder what “severe” means in this context. How does severity affect treatment? What does it mean for a person’s overall health?

In this article, we’ll cover five important things for you to know about severe hemophilia. Thanks to new treatments and knowledge around bleeding disorders, many people live long, healthy lives with hemophilia.

1. Severity Is Defined by Clotting Factor Levels

Hemophilia is an inherited bleeding disorder caused by low clotting factor levels. These specialized proteins help you form blood clots to stop bleeding. There are two main types of hemophilia — A and B.

Hemophilia A, or classic hemophilia, develops when you have low levels of clotting factor VIII (8). Hemophilia B — also known as Christmas disease — develops when you have low levels of factor IX (9). The majority (80 percent) of hemophilia cases are hemophilia A.

Most people with hemophilia are diagnosed as infants or children. Those with a family history of hemophilia are tested early. According to the Centers for Disease Control and Prevention (CDC), the median age for diagnosing severe hemophilia is 1 month old. This means that half of infants diagnosed with severe hemophilia are younger than 1 month and half are older.

Doctors use blood tests for screening and diagnosing cases of hemophilia. A person’s condition is then defined as mild, moderate, or severe based on their clotting factor levels:

• Mild hemophilia — 6 percent to 49 percent of normal clotting factor levels
• Moderate hemophilia — 1 percent to 5 percent of normal clotting factor levels
• Severe hemophilia — Less than 1 percent of normal clotting factor levels

2. Severe Hemophilia Means Higher Risk of Spontaneous Bleeds

For those with severe hemophilia, excessive bleeding can occur spontaneously without an injury or accident. For comparison, people with mild hemophilia have bleeding episodes only from injuries, including those sustained during dental procedures or surgery. Those with moderate hemophilia can have some spontaneous bleeding episodes, but they’re usually caused by an injury.

Joint bleeds that can lead to joint pain and swelling are among the most common symptoms of severe hemophilia A and B. People with either condition are also at a higher risk for internal bleeding in their stomach, intestines, kidneys, urinary tract, and brain. Other less common symptoms of severe hemophilia include nosebleeds and easy bruising.

Some bleeds can become life-threatening if they’re left untreated. For example, brain bleeds can lead to headaches, seizures, and changes in your mental status. If you notice any changes in your behavior or your child’s, call a hemophilia treatment center or your doctor.

Read about what to keep in your hemophilia emergency kit.

3. Severity of Your Hemophilia Likely Won’t Change Over Time

Hemophilia is a genetic condition, meaning it’s caused by changes or mutations in your genes. Specifically, you have gene changes in the instructions to make clotting factors. Most people have mutated genes that are passed down through family members — however, around 20 percent of hemophilia cases are spontaneous.

If you’re born with these mutated genes, your cells simply don’t have the right instructions to make your clotting factors. This means you’ll never be able to make enough of these proteins on your own. Hemophilia severity doesn’t change over time, according to the UCSF Benioff Children’s Hospitals.

If you’re born with severe hemophilia, it won’t improve as you age. The only way to raise your clotting factor levels is with appropriate treatment.

4. Treatments for Severe Hemophilia Reduce Bleeding Risk

The best way to manage severe hemophilia is by sticking closely to your treatment plan. Since people with severe forms of hemophilia have less than 1 percent of normal clotting factor levels, they need to raise them. This is done by infusing clotting factor proteins into a vein in your arm or a port implanted in your chest.

“Prophylaxis” refers to “preventing a disease.” For people with severe hemophilia, prophylactic treatment helps prevent severe bleeding episodes. It can also prevent joint bleeding and damage. Many people receive regular treatment with clotting factor replacement therapy.

This approach uses lab-engineered (recombinant) proteins or concentrated clotting factors donated by other people (human).

Examples of clotting factor VIII concentrates used to treat severe hemophilia A include:

• Antihemophilic factor (human) factor VIII (Monoclate P)
• Antihemophilic factor (recombinant), glycopegylated-exei (Esperoct)
• Antihemophilic factor (recombinant), Fc fusion protein (Eloctate)

Emicizumab-kxwh (Hemlibra) is another prophylactic treatment option for severe hemophilia A. It’s important to note this isn’t a clotting factor treatment. Instead, it’s a monoclonal antibody, or lab-made version of an immune protein, that works by binding to factors IXa (9a) and X (10). These factors are important for helping your blood clot properly. Unlike clotting factors, which are administered intravenously (into a vein), emicizumab-kxwh is injected subcutaneously (under the skin).

Severe hemophilia B may be treated with:

• Coagulation factor IX (recombinant) glycoPEGgylated (Rebinyn)
• Coagulation factor IX (recombinant) (BeneFix)
• Factor IX complex (human) (Konyne 80)

Gene Therapy for Severe Hemophilia

The U.S. Food and Drug Administration (FDA) has now approved two new gene therapies for adults with severe hemophilia. Valoctocogene roxaparvovec-rvox (Roctavian) was approved in June 2023 to treat severe hemophilia A. Entanacogene dezaparovovec-drlb (Hemgenix) was approved earlier in November 2022 for severe hemophilia B. Both gene therapies are given as a one-time intravenous infusion.

Clinical trials for both of these therapies found they both reduce the number of bleeds a person experiences per year. For example, valoctocogene roxaparvovec-rvox treatment in men with severe hemophilia A reduced the average bleeding rate from 5.4 bleeds to 2.6 bleeds per year, according to the FDA. While gene therapy for severe hemophilia doesn’t completely reduce the risk of bleeding, it can help better control it.

If you’re interested in learning more about new treatments or how to better manage your severe hemophilia, talk to your doctor or hematologist (blood disorder specialist).

5. Inhibitors Can Complicate Your Severe Hemophilia Treatment

Clotting factor concentrates are a key part of your severe hemophilia treatment plan. However, around 30 percent of people with severe hemophilia A will develop inhibitors — antibodies that neutralize clotting factors and make hemophilia harder to treat. On the other hand, 3 percent of those with hemophilia B develop inhibitors.

Inhibitors produced by your body recognize the clotting factors as “foreign.” They attack and destroy them, stopping your hemophilia treatment from working. According to the CDC, inhibitors typically develop within your first 50 treatments with clotting factor concentrates. However, your immune system can make them at any time.

While inhibitors technically don’t worsen severe hemophilia, they stop effective treatments from working. This raises your risk of a severe bleeding event and hospitalization. If you have inhibitors, your doctor can prescribe another blood product — known as a bypassing agent — to help.

Living With Severe Hemophilia

The best thing you or your child can do to manage severe hemophilia is stick to the treatment plan. Be sure to take your prophylactic treatment regularly or administer your child’s treatment by following their doctor’s instructions.

Children and adults with severe hemophilia also need to take extra care to avoid injuries. Exercise is important for keeping your joints healthy — but it’s important to choose the right activities. Avoid any contact sports or activities where you may fall down or be hit. Some alternatives include swimming, golf, and cycling.

It is also very important to maintain good oral hygiene. Brush your teeth twice a day with a fluoride-based toothpaste and soft-bristled toothbrush, avoid consumption of sugary foods, and visit your dentist regularly. Such practices are necessary to avoid needing a dental extraction or having to manage troublesome gum bleeds.

Read about the prognosis and life expectancy for hemophilia A.

Talk With Others Who Understand

MyHemophiliaTeam is the social network for people with hemophilia and their loved ones. On MyHemophiliaTeam, more than 6,100 members come together to ask questions, give advice, and share their stories with others who understand life with hemophilia.

Are you living with severe hemophilia? Share your experience in the comments below, or start a conversation by posting on your Activities page.