Haemophilia may lead to a number of problems that require further treatment.

Some people who take blood clotting factor medication may develop certain antibodies in their immune system, known as inhibitors.This happens if the immune system starts to treat clotting factors as foreign objects (like germs) and tries to block their effects.

Poorly-controlled haemophilia can also sometimes lead to joint damage, although this is becoming less common with modern treatments.


Inhibitors can make medication used to treat haemophilia less effective, which means it's more difficult to prevent and control bleeding.

An estimated 20-30% of people who have treatment for severe haemophilia A develop inhibitors. This is much less likely to happen with mild or moderate haemophilia A. Inhibitors usually develop during the first year of treatment, but can occur at any time.

It's rare for someone with haemophilia B to develop inhibitors, but if this does happen, the person could experience life-threatening anaphylaxis during treatment.

People receiving treatment for severe haemophilia A or B should be tested for inhibitors around every three to six months, eventually reducing this to a few times a year. Testing is also required if someone with haemophilia B experiences an allergic reaction to treatment.

People with mild or moderate haemophilia A usually only need a test after receiving intensive treatment, or once a year with normal treatment.

Inhibitors are often temporary, but there are ways of managing the problem if it's persistent.

Immune tolerance induction for haemophilia A

People with severe haemophilia A who develop persistent inhibitors are usually advised to try a treatment programme called immune tolerance induction (ITI). This is carried out at specialist haemophilia care centres.

It involves receiving daily injections of octocog alfa. Over time, the immune system should begin to recognise the blood clotting factors and stop producing inhibitors.

ITI is carried out on a long-term basis, withmost people needing a course of treatment that lasts between6 and 24 months.

Mild or moderate haemophilia Ais usually treated with bypass therapy (see below) or immunosuppressants (medications that reduce the activity of the immune system).

Immune tolerance induction for haemophilia B

ITIis sometimes used to treat persistent inhibitors in haemophilia B.It involves receiving daily injections of nonacog alfa. However, ITI is less successful at treating inhibitors in haemophilia B than it is in haemophilia A,and it carries a risk of anaphylaxis.

Managing a bleed with inhibitors

If someone with inhibitors has a bleed, a medication called a bypass agent must be used.

A bypass agent is a separate product that can be used to stop bleeding when inhibitors are still present. If ITI doesn't work, you may need to use bypass agents for the rest ofyour life.

However, bypass agents can only be used as a response to prolonged bleeding, not as preventative treatment.

Joint damage

Successive joint bleeds can damage cartilage (the soft spongy tissue in joints that acts as a shock absorber) as well as the synovium (a thin layer of tissue that lines the inside of the joint).

The more damaged a joint is, the more vulnerable it is to internal bleeding. This means the joint becomes even more damaged and vulnerable to bleeding.

Joint damage is more common in older adultswith severe haemophilia, because preventative treatments weren't available in the past. It's hoped that modern treatments mean children growing up with haemophilia today won't have joint damage.

Surgery can be used to treat joint damage. If the synovium is damaged, it can be removed so new synovium can grow in its place. If a joint is seriously damaged, it may be necessary to replace the whole joint with an artificial one, such as a hip replacement or knee replacement.

Content supplied by the NHS Website

Medically Reviewed by a doctor on 4 Jan 2017