What is haemophilia?

Haemophilia is an inherited bleeding disorder where the blood doesn't clot properly. It is caused when blood does not have enough clotting factor. A clotting factor factor is a protein in blood that controls bleeding.

  • Haemophilia A (also called classical haemophilia) is the most common form, and is caused by having low levels of factor VIII (8)
  • Haemophilia B (sometimes called Christmas Disease) is caused by having low levels of factor IX (9).

IHaemophilia is not contagious. It is a genetic condition and a person with haemophilia is born with it. It can be inherited and passed on from parent to child.

What causes haemophilia?

Everyone has the gene that makes clotting factor VIII (the factor 8 or F8 gene) and the gene that makes clotting factor IX (the factor 9 or F9 gene). These factors are needed for blood to clot. 

Haemophilia is caused by a change (mutation or alteration) in the F8 or F9 gene. The gene does not work as well as it should. As a result, the body does not make enough factor VIII (8) or factor IX (9) for blood to clot properly.

Who has haemophilia?

In Australia there are more than 3,100 people diagnosed with haemophilia. Both males and females with less than 40% of the normal level of clotting factor are now recognised as having haemophilia.

Most people who have been diagnosed with haemophilia are male. However, around 20-30% of females with the gene change have reduced factor levels and bleeding symptoms and may have haemophilia, usually mild haemophilia.  Severe haemophilia in females is very rare.

What happens when you have haemophilia?

A person with haemophilia does not bleed any faster than anyone else, but bleeding can continue for longer if it is not treated. This results in poor healing. Minor bruising or scratches on the skin are not usually a problem. 

For people with haemophilia, situations become more serious when there is internal or prolonged bleeding. If normal first aid does not stop the bleeding, without other treatment the bleeding can continue for days. Specialised treatment will be needed so blood can clot normally.

Bleeding is most commonly internal. The low levels of clotting factor produce a wide range of bleeding episodes, usually into the joints or muscles. These bleeding episodes, or 'bleeds', may occur spontaneously, without an obvious cause, or as a result of trauma or injury. Specialised treatment is needed and is often infused or injected into a vein. If internal bleeding is not stopped quickly with treatment, it will result in pain and swelling. Over a period of time bleeding into joints and muscles can cause permanent damage such as arthritis, chronic pain and joint damage requiring surgery.

Women and girls may have heavy and/or long menstrual periods. This is called heavy menstrual bleeding or sometimes abnormal uterine bleeding or menorrhagia. It can lead to anaemia (low levels of red blood cells or iron in the body).

Some women may also have heavy bleeding for a long time after childbirth.

It is important for people with haemophilia to involve their haemophilia treating team with any medical or dental procedures or surgery – anything larger than a blood test - to make sure it is managed safely.


Date last reviewed: 29 March 2023

How severe is haemophilia?

People can have mild, moderate or severe haemophilia. The severity of haemophilia depends on the amount of clotting factor in the person's blood.

The normal level of factor VIII or IX in a person’s blood is between 50% and 150%.
Severity and factor level What to expect
Mild haemophilia

5% – 40% of normal clotting factor level

  • Usually only bleeding problems following a bad injury, having teeth taken out, surgery or medical procedures that pierce the skin.
  • Might never have a bleeding problem requiring medical attention.
  • Might not be diagnosed until later in life if not playing contact sports and have not had any injuries or operations.
  • Females might also have bleeding problems with periods (menstruation) or childbirth.
Moderate haemophilia

1% – 5% of normal clotting factor level
  • Might have bleeding problems with minor injuries, such as sporting injuries. 
  • Likely to have bleeding problems after having teeth taken out, surgery, medical procedures and/or a bad injury.
  • Occasionally have a bleeding episode for no obvious reason (‘spontaneous bleeds’).
Severe haemophilia

Less than 1% of normal clotting factor level
  • Often have bleeds into joints, muscles and soft tissues.
  • Can have bleeding episodes for no obvious reason (‘spontaneous bleeds’) as well as after surgery, dental work or injuries including minor bumps and knocks.
Please note: this table is a guide only.
Date last reviewed: August 2020

How is haemophilia diagnosed?

Haemophilia is usually diagnosed through:
  • The physical signs that a person has unusual bleeding problems‚Äč
  • Checking the family history for bleeding problems
  • Laboratory tests on a blood sample for a person’s clotting factor levels. If a person has low factor VIII levels, they have haemophilia A. If they have low factor IX levels, they have haemophilia B. The laboratory tests will show whether they have mild, moderate or severe haemophilia.  
Children with severe haemophilia are usually diagnosed as babies or toddlers. Sometimes this is because there is a family history of haemophilia or a parent or health professional notices unusual bruising or bleeding.

Haemophilia may be suspected if babies have internal bleeding or unusual swelling or bruising after delivery, continue to bleed after a heel prick test, or have excessive bruising or swelling after immunisation.

The most common first signs suggesting haemophilia are:
  • unexplainable recurrent bruises and unusual looking lumps
  • significant bruising or swelling after injections (e.g. immunisations). The bruise may feel quite lumpy and babies may be hesitating to use an arm or leg (e.g. limping)
  • babies crying frequently when an arm or leg is touched or moved
  • warmth and swelling of a joint
  • persistent bleeding after surgery or blood tests.
Mild or moderate haemophilia might not be diagnosed until children are older, or sometimes until they are adults. If they have mild haemophilia, minor injuries may heal normally because there is enough clotting factor activity in the blood. The bleeding problem might not be noticed until the person has surgery, a tooth taken out or a major accident or injury. 

Date last reviewed: August 2020

What is the treatment for haemophilia?

Treatment and care for people with haemophilia involves a team of specialist health professionals to cover the range of their care needs. This is known as ‘comprehensive care’. 

Comprehensive care is coordinated by a Haemophilia Treatment Centre (HTC). 

There is at least one specialist HTC in every state and territory in Australia, which are mostly located in a major public hospital. HTCs have a team of health professionals with expertise in treatment and care for people with bleeding disorders including haemophilia. 

Treatment products

There are a variety of treatment products used to treat haemophilia.
New and emerging treatments for haemophilia

Researchers are always looking for new ways to treat haemophilia.

New treatments are now in development and becoming available.

Some of these new treatments mean less infusions, or that factor is injected into a muscle instead of into a vein. This includes:
  • new types of extended half-life (EHL) therapies
  • non-factor therapies
  • and gene therapies for haemophilia.
Read the latest on new haemophilia therapies in National Haemophilia

Click here to find out more about gene therapy for haemophilia
Clotting factor concentrates

Recombinant factor is the most widely used type of concentrate. This is made by genetic engineering and contains little or no material from human blood or animals. There are several brands available manufactured by different pharmaceutical companies.
Plasma factor concentrates are also used by some people. These are made from the plasma (pale yellow fluid part) in human blood.
Clotting factor concentrate can be given:
  • On demand – before surgery, childbirth or dental treatment, or after an injury or accident, or once a bleed has started.
  • As prophylaxis – taken regularly, weekly to four times a week, to prevent bleeds or reduce bleeding from injury.
Factor concentrates are infused (injected) into a vein at home by parents trained to treat their child, or by people themselves when they are confident enough to do it, or at the Haemophilia Treatment Centre.
Desmopressin (DDAVP)

This is a synthetic hormone which releases the body’s stored factor VIII into the bloodstream to help blood clot. It is used for treating some people with mild haemophilia A. DDAVP can be given as a slow injection into a vein, but may also be given as an injection subcutaneously (into the fatty tissue under the skin).
Tranexamic acid

This slows blood clots from breaking down after they have been formed. It can help to treat mouth or nosebleeds, gut bleeding or bleeding after dental work. Most commonly it is taken as tablets, syrup or in a mouthwash.
Hormone treatment

Hormone treatment, such as oral contraceptives (birth control pills), can help women who have heavy menstrual bleeding. The hormones can increase factor VIII levels.

After treatment with a clotting factor product, some people with haemophilia may develop antibodies – known as ‘inhibitors’ - which make treatment less effective. There are a number of ways to treat inhibitors and many people are successful in overcoming them while others have ongoing problems.
Date last reviewed: May 2023

How is haemophilia passed on?

Haemophilia is an inherited condition and occurs in families; however, in 1/3 of cases it appears in families with no previous history of the disorder. The genetic alteration causing haemophilia is passed down from parent to child through generations.

  • Men with haemophilia will pass the gene alteration on to their daughters but not their sons.
  • Women who carry the gene alteration can pass it on to their sons and daughters.
  • Sons with the gene alteration will have haemophilia.
  • Most women and girls who carry the gene alteration have normal clotting factor levels. Around 20-30% have reduced clotting factor levels. Sometimes their factor levels are low enought to be classified as having haemophilia, usually mild haemophilia. In a few very rare cases girls and women can have extremely low factor levels and have severe haemophilia.
Read more - can females have haemophilia?

The diagrams below may assist in understanding inheritance in haemophilia.
  • The red males have haemophilia
  • The red and blue females carry the gene alteration and some may also have haemophilia. They have one X chromosome with the gene alteration and one unaltered X chromosome.

Haemophilia Genetic Inheritance

Date last reviewed: May 2022

Where can I find more information?


For more information and frequently asked questions – click here - Haemophilia FAQ.

Download the HFA information booklets about haemophilia:

Haemophilia - [PDF, 1.7MB]

Living with mild haemophilia: a guide [PDF, 2.9MB]  

Click here for other HFA publications on haemophilia.


Australian Bleeding Disorders Registry (ABDR) Annual Report 2020-21. Canberra: National Blood Authority, 2021. [PDF, 1.7MB]

Australian Haemophilia Centre Directors' Organisation. Guidelines for the management of haemophilia in Australia. Canberra: National Blood Authority, 2016.

Hermans C, Kulkarni R. Women with bleeding disorders. Haemophilia. 2018;24(Suppl. 6):29-36.

World Federation of Hemophilia. Guidelines for the management of hemophilia. 3rd edn. Montreal: WFH, 2020.


This resource was reviewed by Leonie Mudge and Kate Lenthen from Australia/New Zealand Haemophilia Social Workers’ and Counsellors’ Group; Anne Jackson, Penny McCarthy, Megan Walsh and Claire Bell from Australian Haemophilia Nurses’ Group; Ian d’Young, Abi Polus and Wendy Poulsen from Australian and New Zealand Physiotherapy Haemophilia Group; Katherine Rose, Senior Genetic Counsellor, Monash Medical Centre, Victoria; Dr Chris Barnes, Dr Simon Brown, Dr Simon McRae and Dr John Rowell from Australian Haemophilia Centre Directors’ Organisation; and bleeding disorder community representatives from HFA Haemophilia and Women’s Project Consumer Review Groups.

Inheritance and information about women was reviewed by Dr Julie Curtin, Dr Jane Mason and Dr Stephanie P'ng from Australian Haemophilia Centre Directors’ Organisation in October 2018.

Date last reviewed: March 2023

Important Note: This information was developed by Haemophilia Foundation Australia for education and information purposes only and does not replace advice from a treating health professional. Always see your health care provider for assessment and advice about your individual health before taking action or relying on published information.
This information may be printed or photocopied for educational purposes.