Patient information from BMJ

Ankylosing spondylitis: what is it?

Last published:Mar 21, 2025

Axial spondyloarthritis is a lifelong condition that mainly affects the spine, causing pain and stiffness. There is no cure, but treatments can help relieve the symptoms and keep you active as much as possible.

What is axial spondyloarthritis?

Axial spondyloarthritis (axial SpA) is a type of arthritis that causes inflammation (swelling) in the spine. This can lead to back pain, stiffness, and problems with movement.

There are two types of axial SpA:

• radiographic: where the inflammation in the spine shows up on x-rays. This type of axial SpA is also known as ankylosing spondylitis

• non-radiographic: where the inflammation in the spine doesn’t show up on x-rays.

Axial SpA can sometimes be linked to other problems too, including:

• arthritis in other joints of the body, such as the hips and knees

• ligament and tendon inflammation (known as enthesitis); for example, in the Achilles tendon

• inflammation of the eyes (known as iritis).

Less commonly, people with axial SpA have a higher chance of developing lifelong conditions such as:

• psoriasis (a skin condition that causes scaly, rough patches on skin)

• inflammatory bowel disease (this refers to a group of serious conditions that affect the digestive system).

Axial SpA is a genetic condition. This means that it's caused by the genes you inherit from your parents. It usually begins during the late teenage years or in your early twenties, although it can start earlier or later in life.

What are the symptoms of axial spondyloarthritis?

Axial spondyloarthritis (axial SpA) often takes many years to be properly diagnosed. This is partly because back pain is common, and it can be hard for doctors to tell one type of back problem from another.

The symptoms of axial SpA can include:

• early morning back stiffness that gets better after you have been up and moving around for a while

• pain that alternates from one buttock to another: so you might have pain on one side one day, and on the other side on a different day

• pain that wakes you in the second half of the night which can lead to disturbed sleep

• pain that gets better if you take ibuprofen or another NSAID (non-steroidal anti-inflammatory drug)

• shortness of breath (if axial SpA affects the part of your spine that helps with breathing, or causes the rib joints to stiffen)

• fatigue. 

If you have axial SpA, you’re more likely to develop other conditions, such as:

• iritis: this causes eye pain, redness, light sensitivity, and blurred vision (iritis can lead to blindness if it’s not treated, so it’s important to see your doctor if you notice any of these symptoms)

• enthesitis: this causes pain, swelling, and stiffness at or near other joints

• psoriasis: this looks like scaly, rough patches on the skin

• inflammatory bowel disease: this causes abdominal pain/cramping, diarrhoea, and blood in the stool.

There is no test that can tell for certain whether you have axial SpA. Doctors diagnose it by asking you about your symptoms and examining you.

But some tests can help with diagnosis. For example, an x-ray of your pelvis and lower back might show inflammation of your spine.

If your x-ray is normal and doesn’t show any problems, your doctor might recommend an MRI scan. This can sometimes help to pick up very early inflammation. You might also be offered genetic testing to see if you have the specific gene that’s linked to axial SpA.

What happens next?

If your symptoms and tests suggest you have axial SpA, your doctor will refer you to a specialist to get the best help. Information about treatment for axial SpA is available in our patient information Axial spondyloarthritis: what are the treatment options?

It’s important to know that axial SpA affects everyone differently. You might have a long period of time where the condition doesn’t cause you any problems, and then you may have a ‘flare-up’ that lasts a few weeks. Or, it might get worse over time, which could lead to severe problems in your spine. In some people, bones in the spine can fuse (join) together, causing even more issues with movement.

There is no cure for axial SpA. But staying as active as possible and having regular physiotherapy will help your symptoms. This might be easier for people who have axial SpA that’s less severe.

You will need regular check-ups to assess your levels of pain, stiffness, and fatigue, and whether any joints other than your spine are affected. Your doctor will also want to order regular x-rays of your spine to see whether your axial SpA is getting worse.

Axial SpA doesn’t usually affect how long people live. But there is an increased chance of heart problems with the condition. So your doctor will want to check you regularly for any signs of heart trouble too. 

It’s important to maintain a healthy lifestyle with your diet, and to stop smoking if you currently are. Smoking can affect your heart health, but it can also increase the chances of your axial SpA getting worse.

Many people often join self-help groups to learn more about the condition. These groups can help you keep up with your exercises too and allow you to share your experiences with other people who have axial SpA.