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Health condition · Clinically reviewed

Haemophilia, factor replacement, emicizumab and the era of gene therapy.

An X-linked bleeding disorder with a transformed outlook. Modern care means prophylaxis, subcutaneous options and, for some, a one-off gene therapy.

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Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK clinician before publication.

  • 02

    Sourced from guidance

    Checked against UKHCDO, WFH and NICE guidance, with sources you can see at the end.

  • 03

    Current for 2026

    Reflects modern UK practice including emicizumab prophylaxis and NICE-approved gene therapy.

Key facts

Haemophilia at a glance.

The essentials, in plain English. What it is, the types, and how it is treated in the UK today.

  • What it is

    An X-linked bleeding disorder caused by deficiency of a clotting factor, leading to bleeding into joints, muscles and soft tissues.

  • Haemophilia A

    Factor VIII deficiency, the most common form, affecting roughly 1 in 5,000 male births.

  • Haemophilia B

    Factor IX deficiency, also known as Christmas disease, affecting roughly 1 in 30,000 male births.

  • Haemophilia C

    Factor XI deficiency, autosomal, most often seen in people of Ashkenazi Jewish heritage.

  • Severity

    Severe under 1 percent of factor activity, moderate 1 to 5 percent, mild 5 to 40 percent, guiding bleeding risk and treatment.

  • Modern care

    UKHCDO comprehensive care centres coordinate factor replacement, emicizumab, gene therapy and MDT support.

Why this guide matters

A modern plan, coordinated by a haemophilia centre.

Care has changed dramatically in a decade. The three points below shape everything else on this page.

  • Prophylaxis prevents disability

    Regular factor or emicizumab prophylaxis, started young in severe disease, prevents target joints and lifelong arthropathy.

  • Emicizumab has changed the picture

    A subcutaneous injection every one to four weeks now covers many patients with haemophilia A, including those with inhibitors.

  • Gene therapy is here

    NICE-approved etranacogene dezaparvovec for haemophilia B, and valoctocogene roxaparvovec for haemophilia A, offer a one-off option for selected patients.

How the diagnosis is made

From first bleed to a clear plan.

The steps a UK GP, paediatrician or haematologist will normally follow, in order, so you know what to expect and why.

  1. 01

    Assessing

    Bleeding and family history

    Bruising, joint bleeds, prolonged bleeding after procedures and an X-linked family pattern are the strongest clues.

  2. 02

    Assessing

    Coagulation screen

    A prolonged APTT with normal PT, thrombin time and platelet count points towards a factor VIII, IX or XI deficiency.

  3. 03

    Assessing

    Von Willebrand exclusion

    Von Willebrand disease can mimic mild haemophilia A, so vWF antigen and activity are checked alongside factor VIII.

  4. 04

    Confirming

    Specific factor assays

    Factor VIII, IX and XI activity levels confirm the type and severity, in a specialist commissioned haematology laboratory.

  5. 05

    Confirming

    Inhibitor screening

    A Bethesda assay checks for neutralising antibodies against factor concentrate, especially after treatment exposure.

  6. 06

    Planning

    Genetic testing and counselling

    Molecular testing confirms the causative variant, supports carrier detection in female relatives and enables prenatal diagnosis.

  7. 07

    Planning

    Haemophilia centre MDT

    Care is coordinated by a UKHCDO comprehensive care centre such as the Royal Free, Basingstoke or Manchester, with specialist commissioned funding.

Typical timeline: from first bleed to a comprehensive care plan in weeks.

Symptoms

What haemophilia actually looks like.

The classic mix of joint bleeds, muscle haematomas and mucosal bleeding, and the features that mean it is time to escalate.

  • Haemarthrosis

    Bleeding into knees, elbows and ankles causing warmth, swelling and pain, and long term joint damage if untreated.

  • Muscle haematomas

    Deep bleeds into calf, forearm or iliopsoas muscles that can cause nerve compression and compartment syndrome.

  • Soft tissue bleeding

    Prolonged bruising and haematomas after minor knocks, out of proportion to the injury.

  • Mucosal bleeding

    Recurrent nosebleeds, gum bleeding, gastrointestinal loss or blood in the urine.

  • Chronic arthropathy

    Repeated bleeds into the same target joint drive cartilage loss, stiffness and disability over time.

  • Post-procedural bleeding

    Excessive bleeding after dental work, circumcision, surgery or heel prick tests in neonates.

  • Neonatal presentation

    Intracranial haemorrhage, cephalohaematoma or bleeding after circumcision can be the first sign in severe disease.

  • Red flag - intracranial haemorrhage

    Headache, vomiting, drowsiness or focal signs after any head injury need immediate factor replacement and imaging.

Treatment

How haemophilia is treated in the UK.

Factor replacement first, emicizumab prophylaxis as standard for many, gene therapy for selected patients, and MDT support throughout.

  • Recombinant factor concentrate

    Standard half-life factor VIII or IX given intravenously to treat bleeds and as prophylaxis, with recombinant products preferred over plasma-derived.

  • Extended half-life factors

    Long acting products such as eftrenonacog, rurioctocog, damoctocog and turoctocog allow less frequent infusions, specialist commissioned.

  • Emicizumab (Hemlibra)

    A subcutaneous bispecific antibody that mimics factor VIII, transformational for haemophilia A with or without inhibitors. See our emicizumab clinic.

  • Desmopressin (DDAVP)

    Releases stored factor VIII from endothelium, useful for selected patients with mild to moderate haemophilia A and for minor procedures.

  • Bypassing agents

    Recombinant factor VIIa and activated prothrombin complex (FEIBA) treat bleeds in patients who have developed inhibitors.

  • Immune tolerance induction

    Regular high dose factor exposure to eradicate inhibitors, delivered from a specialist commissioned haemophilia centre.

  • Tranexamic acid

    A useful adjunct for mucosal bleeding, dental extractions and epistaxis, alongside factor replacement.

  • Gene therapy

    Etranacogene dezaparvovec (Hemgenix) for haemophilia B is NICE-approved, with valoctocogene roxaparvovec available for haemophilia A. See our gene therapy clinic.

What this guide is based on

The sources behind every claim on this page.

UKHCDO, WFH, NICE and BSH standards, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your GP or haemophilia centre team knows your history and current treatment, and can tell you which parts apply to you. If in doubt, get seen.

  • UK Haemophilia Centre Doctors Organisation (UKHCDO). Guidelines on the management of haemophilia A and B.

  • World Federation of Hemophilia (WFH). Guidelines for the management of hemophilia, 3rd edition.

  • NICE. Technology appraisal on etranacogene dezaparvovec for treating moderately severe or severe haemophilia B (TA989, 2024).

  • British Society for Haematology. Guidelines on the diagnosis and management of inhibitors in haemophilia.

  • The Haemophilia Society UK. Patient information and advocacy resources.

Red flags

When haemophilia needs urgent attention.

Most bleeds are managed at home or in the haemophilia centre. These are the situations where minutes matter.

  • Suspected intracranial bleed

    Any head injury, or new headache with vomiting, drowsiness or focal signs, needs immediate factor replacement and urgent imaging.

  • Iliopsoas or retroperitoneal bleed

    Groin, hip or lower back pain with reduced hip movement can hide a large bleed and needs urgent factor and imaging.

  • Compartment syndrome

    Tense, painful muscle swelling with neurological or vascular compromise is a surgical emergency.

  • Airway bleeding

    Neck, throat or tongue bleeding can compromise the airway and needs immediate hospital assessment.

  • Inhibitor development

    Loss of response to factor concentrate suggests an inhibitor and needs urgent haemophilia centre review.

  • Neonatal bleeding

    Cephalohaematoma, intracranial bleeding or prolonged bleeding after heel prick or circumcision needs immediate specialist input.

  • Acquired haemophilia in older adults

    New onset unexplained bruising or bleeding in an older adult, or postpartum, can indicate acquired haemophilia with autoantibodies.

  • Suspected GI or urinary bleed

    Melaena, haematemesis or persistent haematuria needs factor cover, investigation and specialist review.

  • Avoid dangerous medicines

    Intramuscular injections, NSAIDs, aspirin and antiplatelet agents can trigger or worsen bleeding and should be avoided.

Living with it

A treatable condition, with a strong safety net.

Four things that make the biggest difference day to day. Prophylaxis, gentle movement, careful planning around procedures and staying close to your haemophilia centre.

A quiet reminder

Consistency beats intensity, every time.

Small, steady habits kept up for years protect joints and prevent bleeds far better than heroic weeks that do not last.

  1. 01 Prophylaxis

    Stay on your regime

    Regular prophylaxis, whether factor infusions or emicizumab, protects joints and prevents disability. Consistency matters more than perfection.

  2. 02 Movement

    Keep muscles strong

    Physiotherapy and low impact activity such as swimming and cycling support joints and reduce bleeds. Contact sports are best avoided.

  3. 03 Planning

    Prepare for procedures

    Tell every dentist, surgeon and anaesthetist about your diagnosis in advance so factor cover, tranexamic acid and monitoring can be arranged.

  4. 04 Support

    Use your haemophilia centre

    Your UKHCDO comprehensive care centre coordinates factor, emicizumab, gene therapy, physiotherapy, psychology and travel advice under one roof.

Frequently asked

Everything we get asked about haemophilia.

Quick answers on inheritance, emicizumab, gene therapy and living safely with a bleeding disorder.

  • What is haemophilia?

    Haemophilia is an inherited bleeding disorder caused by deficiency of a specific clotting factor. Haemophilia A is factor VIII deficiency, haemophilia B (Christmas disease) is factor IX deficiency, and haemophilia C is factor XI deficiency. Severity is graded by factor activity level as severe, moderate or mild.

  • How is haemophilia inherited?

    Haemophilia A and B are X-linked recessive, so they mainly affect boys and men, while women can be carriers and sometimes have symptoms if their factor levels are low. Haemophilia C is autosomal and can affect all sexes. Genetic counselling and carrier testing are offered through UKHCDO haemophilia centres.

  • What is emicizumab and why is it so important?

    Emicizumab (Hemlibra) is a bispecific antibody that mimics the action of factor VIII. It is given as a subcutaneous injection every one to four weeks as prophylaxis in haemophilia A, with or without inhibitors. It has transformed care by reducing bleeds, avoiding intravenous access and simplifying life. Our emicizumab clinic offers full monitoring and support.

  • Is gene therapy available on the NHS?

    Etranacogene dezaparvovec (Hemgenix) for haemophilia B is NICE-approved and available through specialist commissioned centres. Valoctocogene roxaparvovec (Roctavian) for haemophilia A has European approval and is used in selected settings. Our gene therapy clinic assesses suitability, delivers treatment and follows up long term.

  • Which medicines should I avoid?

    Avoid intramuscular injections, aspirin, NSAIDs such as ibuprofen, and antiplatelet drugs unless specifically advised by your haemophilia centre. Paracetamol is generally safe. Always check with your haematology team before starting any new medicine, and carry your haemophilia card and treatment plan.

  • What is acquired haemophilia?

    Acquired haemophilia is a rare autoimmune disorder in which the immune system produces antibodies against factor VIII, most often in older adults, postpartum women or people with malignancy or autoimmune disease. It presents with sudden severe bleeding and needs urgent specialist commissioned haemophilia centre care with bypassing agents and immunosuppression.

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