Acquired hemophilia

Last updated Sept. 19, 2025, by Lindsey Shapiro, PhD
Fact-checked by Joana Carvalho, PhD

Acquired hemophilia is an autoimmune bleeding disorder where the immune system erroneously attacks and neutralizes the body’s healthy blood clotting proteins.

People with the condition are susceptible to spontaneous or excessive bleeding episodes, much like those seen in all people with hemophilia. But while other types of hemophilia are present from birth, usually due to inherited genetic mutations (congenital hemophilia), acquired hemophilia is not inherited and typically develops later in life.

As the rarest form of the disease, acquired hemophilia is estimated to occur in about 1 to 1.5 per 1 million people annually. It affects adults mainly and people of both sexes equally, unlike congenital hemophilia, which usually affects males.

With a prompt diagnosis and appropriate treatment, acquired hemophilia can be pushed into remission, and patients can live full and active lives.

Causes and risk factors

Acquired hemophilia is an autoimmune disease caused when the immune system mistakenly generates antibodies, called inhibitors, against healthy blood clotting proteins. A clotting protein, or coagulation factor, called factor VIII (FVIII), is nearly always the target. Once bound to inhibitors, FVIII cannot work as it should, impairing the blood’s ability to clot and control bleeding.

In about half of all cases, the cause of immune overactivity is never established. This is known as idiopathic acquired hemophilia. For the other 50%, acquired hemophilia is associated with an underlying risk factor, such as:

other inflammatory or autoimmune diseases
cancer
pregnancy or the postpartum period
certain medications, including some antibiotics
infections.

Acquired hemophilia similarly affects males and females, and can occur in people of all races and ethnicities. It most often arises in older adults, with about 80% of those diagnosed being older than 65. It also has an increased incidence in women ages 20-40, which may be related to the higher risk of acquired hemophilia arising during pregnancy and in the period following childbirth. The disease rarely has a pediatric onset.

Symptoms and complications

As with other types of the disease, acquired hemophilia is characterized by symptoms of spontaneous or prolonged bleeding after injury or surgery, but the clinical presentation can look different.

Unlike congenital hemophilia, bleeding into the joints is not a hallmark of acquired hemophilia. Instead, its most common symptoms are extensive bruising and internal bleeding into the body’s soft tissues.

Possible symptoms include:

extensive bruising on the body or the formation of solid swellings of clotted blood (hematomas) from bleeding under the skin
muscle and soft tissue bleeds, leading to pain and mobility issues
blood in the urine or stool from internal bleeding in the urinary or gastrointestinal tract
nosebleeds and gum or mouth bleeding
heavy genital bleeding, especially in women after childbirth
excessive or prolonged bleeding after surgery, dental work, cuts, or other injuries.

The severity of acquired hemophilia varies, from life-threatening spontaneous bleeds to mild bleeding after an injury. Potentially severe complications that may arise include:

severe or life-threatening bleeding in response to injury or surgery
internal bleeding that can damage the brain or other vital organs
compartment syndrome, a painful condition where rapid and significant bleeding into soft tissues compresses and damages muscles, nerves, and blood vessels.

Diagnosis

Because it is so rare, acquired hemophilia can be challenging to diagnose, but a prompt diagnosis is key to preventing serious and life-threatening complications.

The disease may be suspected in a person with new-onset bleeding but without a previous personal or family bleeding history, especially in older adults or women who are pregnant or have recently given birth.

Several blood tests may be run to establish a diagnosis and rule out other bleeding conditions, including:

a complete blood cell count
blood clotting tests, such as prothrombin time (PT) and activated partial thromboplastin time (aPTT)
a measure of FVIII activity levels
a Bethesda assay, to look for FVIII inhibitors.

PT and aPTT evaluate different parts of the blood clotting process. People with acquired hemophilia generally have a blood clotting profile marked by a normal PT but an abnormal aPTT. The aPTT often doesn’t improve when healthy blood is mixed in, which is a sign that inhibitors are present. This test can differentiate acquired hemophilia from congenital hemophilia.

The Bethesda assay is used to detect and quantify inhibitors in people suspected of having acquired hemophilia.

Additional tests can help rule out other disorders, including the presence of lupus anticoagulant, a type of antibody that can increase bleed susceptibility. Levels of von Willebrand factor, a clotting protein that’s deficient in von Willebrand disease, are usually normal in acquired hemophilia.

Treatment options

Treatment for acquired hemophilia takes a two-pronged approach that involves immediate control of active bleeds and long-term elimination of disease-causing antibodies.

Congenital hemophilia is often treated with factor replacement therapy to supply the body with the deficient blood clotting protein. However, that won’t work for most people with acquired hemophilia because existing inhibitors will inactivate the supplied protein.

Instead, bleed control is achieved with bypassing agents, which target different aspects of the clotting process to control bleeding without the need for FVIII. These include:

recombinant factor VIIa (sold as NovoSevenRT or Sevenfact)
activated prothrombin complex concentrate (sold as FEIBA).

Another option for bleed control in acquired hemophilia is Obizur (susoctocog alfa), a lab-made version of FVIII derived from pigs (porcine FVIII) that’s less susceptible to being targeted by human inhibitors.

The ultimate goal of acquired hemophilia treatment is to induce a state of remission in which the inhibitor titer is low or absent, bleeding does not occur, and clotting factor activity remains normal without active treatment.

While rare cases of spontaneous remission are possible, achieving this goal typically requires immunosuppressive agents to halt inhibitor production. The standard protocol involves corticosteroids (e.g. prednisone), often combined with the chemotherapy agent cyclophosphamide. It may also include:

nonsteroidal medications, such as mycophenolate mofetil, cyclosporine A, or azathioprine
rituximab, which lowers the levels of antibody-producing immune cells
plasmapheresis and immunoadsorption, which are procedures that can be used to remove inhibitors from the blood.

If a known disease trigger has been identified, treatment or management of this underlying condition is also important for sustained disease control.

Prognosis and long-term management

With advances in diagnosis and treatment, the long-term outlook for people living with acquired hemophilia has improved.

About 60%-80% of patients will achieve remission with appropriate disease management, although disease recurrence may occur in about a quarter of them. Proactive monitoring is critical so disease recurrence can be identified and managed promptly.

Patients can take several steps to support their overall health, prevent bleeding, and make living with hemophilia easier. These include:

avoiding activities with a high injury risk
discussing all medications with a healthcare provider, as some drugs can make bleeding worse
maintaining good dental hygiene, to avoid gum and mouth bleeding
talking with a hemophilia treatment team before any surgery or invasive procedure
engaging in regular and appropriate exercise
maintaining a good support system and keeping track of mental health needs.

With a comprehensive care and management plan, people with acquired hemophilia can live full and active lives.

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