In short
Ankylosing spondylitis (AS) is the best-known form of spondyloarthritis — inflammation of the spine and pelvis that causes back pain and stiffness which improve with movement and get worse with rest. Early diagnosis, medication and daily exercise protect the spine's flexibility.
On this page
What is ankylosing spondylitis?
Spondyloarthritis is a family of inflammatory conditions affecting the spine and the points where tendons and ligaments attach to bone. Ankylosing spondylitis is its best-known form, usually starting in the lower back and pelvis.
With early diagnosis and the right treatment, most people stay active and keep the condition under control.
What are the symptoms of AS?
- Lower back and buttock pain Long-lasting, and often the first sign.
- Morning stiffness In the spine or hips, lasting over 30 minutes.
- Less flexibility Bending and twisting slowly get harder.
- Heel pain Where tendons attach to bone (GlossaryEnthesitisInflammation where a tendon or ligament attaches to bone, often at the heel or the sole of the foot.All terms A–Z).
- Other joints Hips, shoulders or knees may ache or swell.
- Red, painful eye GlossaryUveitisInflammation inside the eye causing redness, pain and sensitivity to light. It needs prompt treatment.All terms A–Z — get it checked promptly.
How is AS diagnosed?
- History and examination Your pattern of back pain and any family history.
- Imaging X-rays of the lower spine and pelvis; MRI shows inflammation much earlier.
- Blood tests The GlossaryHLA-B27A gene marker found in most people with ankylosing spondylitis. Many people carry it without the condition, so it supports a diagnosis rather than proving one.All terms A–Z gene marker and inflammation markers — supportive, not conclusive on their own.
- Movement tests Measuring spinal flexibility and chest expansion.
How is AS treated?
- Exercise and physiotherapy A cornerstone of treatment for strength, flexibility and posture.
- Anti-inflammatories NSAIDs such as ibuprofen or naproxen usually come first.
- Biologics TNF or IL-17 blockers for more active disease.
- DMARDs Help joints outside the spine, less so the spine itself.
- Healthy habits Good posture, a healthy weight and staying active.
What is the outlook?
- With steady treatment, most people manage pain well and stay active.
- Untreated inflammation can fuse the spine over time; treatment and exercise prevent or slow this.
- Modern biologics mean far fewer people develop the severe stiffness seen in the past.
Questions patients ask
Is swimming good for ankylosing spondylitis?
Yes. Water supports your weight, so swimming and stretching improve flexibility without straining joints. Warm-pool physiotherapy (hydrotherapy) helps many people even more than exercise on land.
What makes AS worse day to day?
Long spells of sitting and slouching. Move regularly, use supportive seating and keep an eye on your posture.
Can the spine fuse, and can it be prevented?
Left untreated, the vertebrae can slowly fuse. Consistent medicine, exercise and physiotherapy prevent or significantly slow this — so keep going even when you feel well.
Does AS affect fertility or pregnancy?
AS does not affect fertility. Some medicines need adjusting, so plan ahead; with good care, women with AS can have safe pregnancies.
Words worth knowing
Full glossary- ESR / CRP
- Blood tests that measure inflammation in the body. Useful for tracking disease activity, but they do not point to any one condition.
- Enthesitis
- Inflammation where a tendon or ligament attaches to bone, often at the heel or the sole of the foot.
- HLA-B27
- A gene marker found in most people with ankylosing spondylitis. Many people carry it without the condition, so it supports a diagnosis rather than proving one.
- Sacroiliitis
- Inflammation of the sacroiliac joints, where the spine meets the pelvis — often the earliest change seen on scans.
- Uveitis
- Inflammation inside the eye causing redness, pain and sensitivity to light. It needs prompt treatment.
This page is intended for general patient education and does not replace personalized medical advice. Please consult your rheumatologist about your specific symptoms, diagnosis, or treatment plan. Last updated 3 October 2026.