The symptoms of ankylosing spondylitis (AS) usually develop slowly over several months or years. The symptoms may come and go, and improve or get worse, over many years.

AS usually first starts to develop during the later teenage years or early adulthood.

The main symptoms of AS are described below, although you may not develop all of these if you have the condition.

Back pain and stiffness

Back pain and stiffness are usually the main symptoms of AS. You may find:

the pain gets better with exercise, but doesn’t improve or gets worse with rest

the pain and stiffness is worse in the morning and at night – you may wake up regularly during the night because of the pain

you have pain in the area around your buttocks

Arthritis

As well as causing symptoms in your back and spine, AS can also cause inflammation of the joints (arthritis) in other parts of your body, such as your hips and knees.

The main symptoms associated with arthritis are:

pain on moving the affected joint

tenderness when the affected joint is examined

swelling and warmth in the affected area

Enthesitis

Enthesitis is painful inflammation where a bone is joined to a tendon (a tough cord of tissue that connects muscles to bones) or a ligament (a band of tissue that connects bones to bones).

Common sites for enthesitis are:

at the top of the shin bone

behind the heel (Achilles tendon)

under the heel

where the ribs join the breast bone

If your ribs are affected, you may experience chest pain and find it difficult to expand your chest when breathing deeply.

Fatigue

Fatigue is a common symptom of untreated AS. It can make you feel tired and lacking in energy.