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.

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.