Haemophilia is a rare condition that affects the blood's ability to clot. It's usually inherited, and most people who have it are male.

Normally, when you cut yourself, substances in your blood known as clotting factors mix with blood cells called platelets to make the blood sticky.  This makes the bleeding stop eventually.

People with heamophilia do not have as many clotting factors as there should be in the blood. This means they bleed for longer than usual.

Symptoms of haemophilia

The symptoms of haemophilia can be mild to severe, depending on the level of clotting factors you have.

The main symptom is that bleeding does not stop.

People with haemophilia may have:

  • nosebleeds that take a long time to stop
  • bleeding from wounds that lasts a long time
  • bleeding gums
  • skin that bruises easily
  • pain and stiffness around joints, such as elbows, because of bleeding inside the body (internal bleeding)

When to get medical advice

See your GP if:

  • you or your child bruises easily and has bleeding that does not stop
  • you or your child has symptoms of joint bleeds - for example, tingling, pain, or stiffness in the joint, and the joint becoming hot, swollen and tender
  • you have a family history of haemophilia and you're pregnant or planning to have a baby

There's a small risk people with haemophilia may have a bleed inside their skull (a brain or subarachnoid haemorrhage).

Symptoms of a brain haemorrhage include:

  • a severe headache
  • a stiff neck
  • being sick (vomiting)
  • a change in mental state, such as confusion
  • speaking difficulties, such as slurred speech
  • changes in vision, such as double vision
  • loss of co-ordination and balance
  • paralysis of some or all of the facial muscles

Call 999 for an ambulance is you think someone's bleeding inside the skull.

Your local haemophilia centre

If you have haemophilia, register at your local haemophilia centre. It's a useful source of advice and support.

People with haemophilia are cared for by a hospital haematology department.

Tests and diagnosis

Blood tests can diagnose haemophilia and find out how severe it is.

If there's no family history of haemophilia, it's usually diagnosed when a child begins to walk or crawl.

Mild haemophilia may only be discovered later, usually after an injury or a dental or surgical procedure.

Genetic tests and pregnancy

If you have a family history of haemophilia and you're planning to get pregnant, genetic testing and counselling can help determine the risk of passing the condition on to a child.

This may involve testing a sample of your tissue or blood to look for signs of the genetic change that causes haemophilia.

Tests during pregnancy can diagnose haemophilia in the baby. These include:

  • chorionic villus sampling (CVS) – a small sample of the placenta is removed from the womb and tested for the haemophilia gene, usually during weeks 11 to 14 of pregnancy
  • amniocentesis – a sample of amniotic fluid is taken for testing, usually during weeks 15 to 20 of pregnancy

There's a small risk of these procedures causing problems such as miscarriage or premature labour, so you may want to discuss this with your doctor.

If haemophilia is suspected after your child's born, a blood test can usually confirm the diagnosis. Blood from the umbilical cord can be tested at birth.

Treatments for haemophilia

There's no cure for haemophilia, but treatment usually allows a person with the condition to enjoy a good quality of life.

Genetically engineered clotting factor medicines are used to prevent and treat prolonged bleeding. These medicines are given as an injection.

In milder cases, injections are usually only given in response to prolonged bleeding. More severe cases are treated with regular injections to prevent bleeding.

Living with haemophilia

With treatment, most people with haemophilia can live a normal life.

However, you should:

  • avoid contact sports, such as rugby
  • be careful taking other medicines - some can affect your blood's ability to clot, such as aspirin and ibuprofen
  • take care of your teeth and gums and have regular check-ups at the dentist

Looking after your teeth and gums helps avoid problems such as gum disease, which can cause bleeding. Most non-surgical dental treatment can be carried out at a general dental surgery.

Your care team at the hospital can give you advice about surgical dental procedures, such as having a tooth removed, and further information and advice about living with haemophilia.

Information about you

If you have haemophilia, your clinical team may pass information about you on to the National Congenital Anomaly and Rare Diseases Registration Service (NCARDRS).

This helps scientists better understand the condition. You can opt out of the register at any time.

Find out more about the register.



The symptoms of haemophilia depend on how severe the condition is, but the main sign is prolonged bleeding.

The bleeding may occur spontaneously. For example, this could be:

  • sudden nosebleeds
  • bleeding gums
  • joint bleeds (bleeding inside your joints, such as elbows)
  • muscle bleeds

The bleeding may also occur after a medical procedure, such as having a tooth removed.

The severity of haemophilia is determined by the level of clotting factors in a person's blood:

  • mild haemophilia – between 5 and 50% of the normal amount of clotting factors
  • moderate haemophilia – between 1 and 5% 
  • severe haemophilia – less than 1% 

Find out when to seek emergency medical help.

Mild haemophilia

Children born with mild haemophilia may not have any symptoms for many years.

The condition usually only becomes apparent after a significant wound or surgery, or a dental procedure such as having a tooth removed. These events could cause unusually prolonged bleeding.

Moderate haemophilia

Children with moderate haemophilia are affected in the same way as those with mild haemophilia, but also bruise easily.

They may also have symptoms of internal bleeding around their joints, particularly if they have a knock or a fall that affects their joints. This is known as a joint bleed.

The symptoms usually begin with a tingling feeling of irritation and mild pain in the affected joint – most commonly the ankles, knees, and elbows. Less commonly, the shoulder, wrist, and hip joints can also be affected.

If a joint bleed isn't treated, it can lead to:

  • more severe joint pain
  • stiffness
  • the site of the bleed becoming hot, swollen, and tender

Severe haemophilia

The symptoms of severe haemophilia are similar to those of moderate haemophilia. However, joint bleeding is more frequent and severe.

Children with severe haemophilia have spontaneous bleeding. This means they start bleeding for no apparent reason.

For example, this could be:

  • nosebleeds
  • bleeding gums
  • joint bleeds
  • muscle bleeds

Without treatment, people with severe haemophilia can develop:

  • joint deformity, which may require replacement surgery
  • soft tissue bleeding
  • serious internal bleeding

When to seek emergency medical help

There's a small risk of bleeding inside the skull, known as an intracranial haemorrhage. It's estimated 3% of people with moderate or severe haemophilia will have an intracranial haemorrhage. 

However, spontaneous bleeding inside the skull is uncommon and usually only caused by a head injury.

Bleeding in the skull should be treated as a medical emergency.

The symptoms of an intracranial haemorrhage include:

  • a severe headache
  • a stiff neck
  • vomiting
  • a change in mental state, such as confusion
  • speaking difficulties, such as slurred speech
  • changes in vision, such as double vision
  • loss of co-ordination and balance
  • paralysis of some or all of the facial muscles

Call 999 for an ambulance if you think someone is bleeding inside the skull.

Who can get it

Haemophilia is caused by an inherited genetic mutation, which mainly affects males.

A genetic mutation is a permanent alteration in the DNA sequence that makes up a gene. This means that some of the body's processes won't work in the normal way.

The type of mutation determines whether a person will experience mild, moderate or severe symptoms.

How the mutation is inherited

The gene mutation is found on the X chromosome. It can be carried by either the mother or father, or both.

You can read more about chromosomes and how we inherit mutations by reading about genetics.

The chances of a child inheriting the haemophilia mutation depend on which of their parents has the mutated gene.

Only the mother has the mutated gene

If a woman with the mutated chromosome and an unaffected man have a baby, there's a:

  • one in four chance of having an unaffected baby boy
  • one in four chance of having a baby boy with haemophilia
  • one in four chance of having an unaffected baby girl
  • one in four chance of having a baby girl with an affected X chromosome

In the last situation, the girl becomes a carrier of the mutated gene. This means she can pass it on to her children, but won't usually have any severe symptoms of haemophilia herself.

However, some female carriers sometimes have bleeding problems, such as heavy periods.

Only the father has the mutated gene

If a man with haemophilia has a son with an unaffected woman, there's no chance the boy will get haemophilia.

This is because he always inherits his X chromosome from his mother, who in this case doesn't have the mutated gene.

However, any daughters the man has will become carriers of the mutated haemophilia gene and may pass it on to their children. 

Both parents have the mutated gene

If a woman with the mutated chromosome and a man with haemophilia have a baby, there's a:

  • one in four chance of having an unaffected baby boy
  • one in four chance of having a baby boy with haemophilia
  • one in four chance of having a baby girl who's a carrier of haemophilia
  • one in four chance of having a baby girl with haemophilia

This means it's possible for a female to have haemophilia, although it's very rare.

No family history

In some cases, a boy is born with haemophilia even though there's no family history of the condition.

In such cases, it's thought the mutation developed spontaneously in the boy's mother, grandmother or great-grandmother, but until then a male member of the family had never inherited the mutated gene.

Some studies have shown there's no known family history of haemophilia in up to a third of new cases.

How haemophilia affects the blood

Blood cells called platelets are very important for blood clotting. These cells have a sticky surface that allows them to clump together to stop the flow of blood.

Platelets also need clotting factors. These are proteins that form a "web" around the platelets, helping them to stay in place.

The mutated haemophilia gene means a child with the condition doesn't have enough clotting factors in their blood.

Several different clotting factors are present in the blood. They are numbered using roman numerals.

For example, in haemophilia A there's not enough clotting factor VIII (8) in the blood. In haemophilia B, there's not enough clotting factor IX (9) in the blood.


The recommended treatment plan for haemophilia depends on how severe it is.

There are 2 main approaches to treatment:

  • preventative treatment, where medicine is used to prevent bleeding and subsequent joint and muscle damage
  • on-demand treatment, where medicine is used to treat prolonged bleeding

Haemophilia is usually treated by a team at a haemophilia hospital department.

Preventative treatment

Most cases of haemophilia are severe and need preventative treatment. This involves regular injections of clotting factor medicine.

If your child has haemophilia, you'll be trained to give them the injections when they're young.

They'll be taught how to inject themselves when they're older, to help avoid regular hospital appointments.

In some cases, injections may be given into a device called an implantable port, which can be surgically placed under the skin.

This port is connected to a blood vessel near the heart, so you don't need to try to find a vein for every injection.

People who have preventative treatment will need regular follow-up appointments with their care team so their progress can be monitored.

Preventative treatment is usually continued for life. It may be possible for someone to change to on-demand treatment, but they may be advised to switch back to preventative treatment if they have any episodes of significant bleeding.

There are different types of haemophilia. This page covers the most common types: haemophilia A and haemophilia B. They have similar symptoms, but need different treatments because different clotting factors are affected. 

Haemophilia A

Preventative treatment for haemophilia A involves regular injections of a medicine called octocog alfa (Advate).

This medicine is an engineered version of clotting factor VIII (8), the clotting factor people with haemophilia A do not have enough of. Injections every 48 hours are often recommended.

Side effects of octocog alfa are uncommon, but can include:

  • an itchy skin rash
  • redness and soreness at the site of the injection.

Haemophilia B

Preventative treatment for people with haemophilia B involves regular injections of a medicine called nonacog alfa (BeneFix).

This is an engineered version of clotting factor IX (9), which people with haemophilia B do not have enough of. Injections twice a week are often recommended.

Side effects of nonacog alfa are uncommon, but can include:

  • headaches
  • altered taste
  • feeling sick (nausea)
  • discomfort and swelling at the injection site.

On-demand treatment

In mild or moderate cases, treatment for haemophilia may only be necessary as an immediate response to bleeding.

Haemophilia A

People with haemophilia A can be treated on-demand with injections of octocog alfa or a medicine called desmopressin.

Desmopressin is a synthetic hormone. It works by stimulating the production of clotting factor VIII (8) and is usually given by injection.

Possible side effects of desmopressin include

  • headache
  • stomach pain
  • feeling sick (nausea)

Haemophilia B

On-demand treatment for haemophilia B usually involves injections of nonacog alfa.

Complications of haemophilia

Complications can include:

  • developing inhibitors in your immune system
  • joint problems.


Some people who take blood clotting factor medicine develop antibodies in their immune system, called inhibitors, that make the medicine less effective.

People having treatment for haemophilia should be regularly tested for inhibitors.

Inhibitors can be treated with immune tolerance induction (ITI). This involves daily injections of clotting factors so the immune system should begin to recognise them and stop producing inhibitors. 

ITI is usually offered to people with severe haemophilia A. People with haemophilia B may be offered ITI, but it's less effective and there's a risk of severe allergic reaction.  

People with mild or moderate haemophilia A who develop inhibitors may be offered either bypass therapy or immunosuppressants. 

Bypass therapy uses a medicine called bypass agent to stop bleeding when it happens.

Immunosuppressants are medicines that suppress your immune system.

Joint damage

Joint bleeds can damage the soft spongy tissue in your joints (cartilage), and the thin layer of tissue lining the inside of the joint (synovium). The more damaged a joint is, the more vulnerable it is to bleeding.

Joint damage is more common in older adults with severe haemophilia. It's hoped that modern treatments mean children growing up with haemophilia today will not have joint damage.

Surgery can be used to remove damaged synovium so new synovium can grow. Serious damage to a joint may mean it needs to be replaced – for example, a hip replacement or knee replacement.

The information on this page has been adapted by NHS Wales from original content supplied by NHS UK NHS website nhs.uk
Last Updated: 24/10/2022 12:25:15