Complications of ankylosing spondylitis 

Ankylosing spondylitis (AS) is a complex condition that can affect many parts of your body. It can cause complications in your day-to-day life and lead to additional health conditions.

Some complications associated with AS are outlined below.

Reduced flexibility

Although most people with AS remain fully independent or minimally disabled in the long term, around 4 in every 10 people with the condition will eventually have severely restricted movement in their spine.

This usually only affects the lower back and is the result of the bones in the spine fusing (joining up).

Fusing of the spine can make it difficult to move your back and can mean your posture becomes fixed in one position, although it doesn't lead to severe disability in most cases.

In rare cases, surgery may be recommended to correct severe bends in the spine.

Joint damage

AS can cause joints such as the hips and knees to become inflamed. This can damage the affected joints over time, making them painful and difficult to move.

If a joint becomes particularly damaged, you may need surgery to replace it with an artificial one.


Iritis, also known as anterior uveitis, is a condition sometimes associated with AS where the front part of the eye becomes red and swollen. It usually only affects one eye, rather than both.

If you have iritis, your eye may become red, painful and sensitive to light (photophobia). Your vision may also become blurred or cloudy.

You should visit your GP as soon as possible if you have AS and think you may have developed iritis, as the condition can cause the loss of some or all of your vision if not treated promptly.

If your GP thinks you have iritis, they will refer you urgently to an ophthalmologist (a medical doctor who specialises in eye problems) for treatment.

Iritis can usually be treated with corticosteroid eye drops.

Osteoporosis and spinal fractures

Osteoporosis is where the bones become weak and brittle. In AS, osteoporosis can develop in the spine and can increase your risk of fracturing the bones in your backbone. The longer you have the condition, the more this risk increases.

If you do develop osteoporosis, you will usually need to take medication to help strengthen your bones. There are a number of medications that can be used to treat osteoporosis, which can be taken by mouth (orally) as tablets or given by injection.

Read more about treating osteoporosis.

Cardiovascular disease

If you have AS, you may also have an increased risk of developing cardiovascular disease (CVD). CVD is a general term that describes a disease of the heart or blood vessels, such as heart disease and stroke.

Due to this increased risk, it is important to take steps to minimise your chances of developing CVD.

Your rheumatologist (a specialist in treating muscle and joint conditions) can advise about lifestyle changes you should make to minimise your risk of developing a CVD. These changes may include:

You may also be prescribed medication to reduce your blood pressure or blood cholesterol level.

Cauda equina syndrome

Cauda equina syndrome is a very rare complication of AS that occurs when nerves at the bottom of your spine become compressed (compacted).

Cauda equina syndrome causes:

  • pain or numbness in your lower back and buttocks
  • weakness in your legs – which can affect your ability to walk
  • urinary incontinence or bowel incontinence (when you cannot control your bladder or bowels)

See your GP as soon as possible if you have AS and you develop any of these symptoms.


In very rare cases, it is possible to develop a condition called amyloidosis as a complication of AS.

Amyloid is a protein produced by cells in your bone marrow (the spongy material found in the centres of some hollow bones). Amyloidosis is a condition where amyloid builds up in organs such as your heart, kidneys and liver.

Amyloidosis can cause a wide range of symptoms, including fatigue, weight loss, fluid retention (oedema), shortness of breath and numbness or tingling in the hands and feet.

Problems with employment

Over time, AS can increasingly affect your ability to work. Some people with the condition may be unable to work at all and others may need changes to their working life, such as working part-time, working from home or avoiding physically demanding work.

When at work, it is important to maintain a good posture when sitting or standing for long periods of time. You should get up, stretch and move around regularly. This could mean adjusting your work station or ensuring you take regular breaks. Read more about how to sit correctly.

The National Ankylosing Spondylitis Society (NASS) has more information on living with Ankylosing Spondylitis, including advice about the condition and employment.

Page last reviewed: 26/06/2014

Next review due: 26/06/2016