Haemophilia is a condition which means the blood does not clot properly. There are two types of haemophilia - haemophilia A, and the rarer haemophilia B. Both have different precise causes but the same symptoms.1 Haemophilia more commonly affects males, but females can also have haemophilia, although usually less severely than males.1
What is haemophilia?
Haemophilia is a rare condition where the blood does not clot properly. This can result in prolonged bleeding (bleeding that lasts longer than usual) and, in severe cases, spontaneous internal bleeds (bleeding that happens inside the body for no clear reason).
There are proteins in the body called factor which help to form blood clots to control bleeding.2
In haemophilia, not enough of these clotting factors are made, with one of the clotting factor proteins either partly or completely missing. This means that people with haemophilia take longer than normal for bleeding to stop after an injury.3
• Haemophilia A is a deficiency of factor VIII (8).3
• Haemophilia B (also known as Christmas Disease) is a deficiency of factor IX (9).3
The lower the clotting factor level, the more risk there is in terms of your body's ability to stop bleeding.
How common is haemophilia?
Haemophilia A affects about 1 in 5,000 male births, whereas haemophilia B is rarer, affecting around 1 in 25,000 male births in the UK.1 Severe and moderate forms of haemophilia are rare in women, but around 20% of those with mild haemophilia are female.4 In fact, over 1000 women with haemophilia are registered in the National Haemophilia Database, making up over 10% of diagnosed people with haemophilia in the UK.5
What are the symptoms of haemophilia?
The symptoms of haemophilia A and B are the same and include:1,6
- Bruising easily
- Bleeding into joints, which may cause:
- Pain, stiffness and/or swelling
- Difficulty straightening
- Bleeding into muscles which may cause:
o Pain, tenderness and/or swelling
o Numbness and/or pins and needles - Prolonged bleeding after surgery or having a tooth extracted
Learn more about living with haemophilia at Liberate Life
Liberate Life is a platform which provides practical information and insights to help people with haemophilia to pursue personal aspirations, manage the challenges of haemophilia, and make the most of care and treatment.
It represents a shared journey of empowerment, progress and living with greater freedom and confidence.
How is haemophilia diagnosed?
If an individual is showing some or all of the symptoms of haemophilia, a formal diagnosis may be recommended, especially if there is a family history of haemophilia. The individual may be invited to take a general blood test, or screening, for blood clotting. If haemophilia is suspected, the next step might be referral for specific tests at a haemophilia treatment centre for factor VIII and factor IX.1
Haemophilia is usually an inherited condition, passed on from parents to children. However, in about a third of cases of haemophilia A and B there is no family history of the condition.7
Haemophilia severity levels and what they mean1
Haemophilia is classed as mild, moderate or severe depending based on the baseline level of clotting factor a person has, as measured in a laboratory test. The same measures are used for haemophilia A and B
Mild haemophilia
When bleeds typically occur
Bleeding usually only occurs following injury, surgery or having a tooth out. Women may have heavy periods
Moderate haemophilia
When bleeds typically occur
Bleeding as a result of minor injury
Severe haemophilia
When bleeds typically occur
Bleeding into joints and muscles, often with no obvious cause
Are there any other conditions similar to haemophilia A or B?
Other rare bleeding disorders exist:
- Haemophilia C, also known as Rosenthal syndrome8, is caused by factor XI deficiency.9 It affects about 1 person per million,8 far fewer people than haemophilia A or B.
- Von Willebrand Disease, a genetic bleeding disorder where patients have a deficient or defective von Willebrand factor (VWF), a protein in the blood that is important to stop bleeding.10
- Very rarely, individuals may be born with, or develop: Factor I Deficiency, Factor II Deficiency, Factor V Deficiency, Factor VII Deficiency, Factor X Deficiency, Factor XII Deficiency, or Factor XIII Deficiency.11
- Immune thrombocytopenia (ITP), a rare autoimmune disease affecting platelet production and characterised by fatigue, bruising and bleeding.12 Some symptoms are similar to haemophilia.
Our Global Commitment: World Federation of Hemophilia (WFH) Humanitarian Aid Program
The majority of people living with bleeding disorders around the world still do not have access to treatment or care.13
Together with Sanofi, we intend to donate up to 1 billion international units (IUs) of factor replacement for use in developing countries.
Mont Blanc - Mountains we carry; Mountains we climb
The story of seven people with haemophilia who set out to conquer the highest peak in the Alps - a powerful testament to the strength, resilience and determination of the bleeding disorder community.
This inspiring expedition reminds us of the importance of reaching new heights - no matter the obstacles in our way.
A Different Future: Then and Now
Growing up with haemophilia today a very different experience to the past.
In this short film, Charlie heads to the park to play football. While he plays, his mum Helen talks with Paul, who also has haemophilia. As they chat, Helen hears just how much as changed since Paul was a child.
Adam the Adventurer
A series of books, endorsed by The Haemophilia Society, aimed at supporting children with haemophilia to understand and navigate living with the condition.
Patient Organisations
Haematology
The area of medicine dealing with diseases of the blood
References:
- The Haemophilia Society: Understanding Haemophilia
https://haemophilia.org.uk/wp-content/uploads/2017/04/Understanding_haemophilia_WEB.pdf - The Cleveland Clinic: What is hemophilia
https://my.clevelandclinic.org/health/diseases/14083-hemophilia - The Haemophilia Society: Haemophilia
https://haemophilia.org.uk/bleeding-disorders/haemophilia-a-and-b/ The Haemophilia Society: How common is haemophilia
The Haemophilia Society: Underserved – Overlooked: How our health systems are failing women and girls with a bleeding disorder
NHS: Haemophilia
Irish Haemophilia Society: Inheritance of haemophilia
https://haemophilia.ie/about-bleeding-disorders/haemophilia/inheritance-2/
Thejus, J. et al. Hemophilia C: A Case Report With Updates on Diagnosis and Management of a Rare Bleeding Disorder. National Library of Medicine.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7153668/- The Haemophilia Society: Factor XI deficency Factsheet
https://haemophilia.org.uk/wp-content/uploads/pdf/factsheet_factorXI.pdf - bleedingdisorders.com: What is von Willebrand Disease (VWD)?
https://www.bleedingdisorders.com/about/von-willebrand-disease - bleedingdisorders.com: Other rare bleeding disorders
https://www.bleedingdisorders.com/about/types-of-bleeding-disorders Cleveland Clinic: Immune Thrombocytopenia
Immune Thrombocytopenia (ITP): Symptoms, Diagnosis & Treatment
World Federation of Hemophilia: Annual Report 2024
Sep, 2025