Ankylosing spondylitis (AS) is a chronic inflammatory condition that primarily targets the spine’s joints and ligaments. In its early stages, AS often presents as pain and stiffness in the lower back, especially noticeable after periods of rest. Additional early indicators may include fatigue, neck discomfort, and unintended weight loss.

Symptoms tend to appear gradually and may come and go over time. Many individuals with AS experience cycles of symptom flare-ups and remission.

Lower Back Pain and Stiffness

pain and stiffness in the lower back
These are the most frequent symptoms of AS and stem from inflammation in the sacroiliac joints, located between the pelvic bones and the base of the spine. The discomfort usually begins slowly and may start as a dull ache on one side. Pain is often worse at night or after long periods of inactivity, but light activity or warm baths often help ease symptoms.

Joint Pain

spread to other joints
Inflammation from AS can also affect the hips, shoulders, ankles, knees, and elbows. The degree of pain differs between individuals. As the condition progresses, inflammation between the spine and ribs may intensify, potentially making deep breathing more difficult.

Enthesitis

inflammation of tendon-bone connections
Enthesitis is common in AS and causes pain and tenderness where tendons or ligaments attach to bone. This often affects the heels but can occur elsewhere. Over time, it may lead to bone loss or abnormal bone growth, which can result in bone spurs—painful, bony projections forming on existing bones.

Fatigue

widespread tiredness and low energy
Nearly all individuals with AS report fatigue. This can be due to chronic pain disrupting sleep, the body using extra energy to manage inflammation, and the emotional toll of dealing with a long-term illness.

Anterior Uveitis

inflammation of the eye’s middle layer
Also known as iritis, anterior uveitis affects the iris and can cause sudden eye pain, redness, sensitivity to light, and blurry vision. This condition requires immediate attention from an eye care professional. If untreated, it may result in severe complications like glaucoma, cataracts, or even permanent vision loss.

Limited Mobility

reduced flexibility and movement
Inflammation may stiffen the spine and joints, limiting motion. In more advanced stages, spinal bones (vertebrae) may fuse together, leading to a hunched-forward posture.

Other Symptoms

involvement beyond the spine
AS can affect several body systems, producing a wide range of additional symptoms including:

  • Chest pain

  • Breathing difficulty

  • Irregular heartbeat

  • Loss of appetite and unintentional weight loss

  • Skin rashes

  • Digestive or gastrointestinal issues

Flare Symptoms

cycles of symptom worsening
AS flares vary in severity and duration, ranging from a few days to several weeks. They can be either localized (affecting specific areas) or generalized (affecting multiple areas).

Common flare symptoms include:

  • Fatigue

  • Increased pain and stiffness in the lower back or neck

  • Reduced appetite and weight loss

  • Mild fever

  • Changes in mood

  • Joint tenderness in shoulders, hips, ribs, or knees

Symptoms in Children

juvenile ankylosing spondylitis (JAS)
Although most diagnoses occur in adulthood, some people experience symptoms in childhood. JAS is more common in boys and typically involves:

  • Nighttime or early morning back stiffness and pain

  • Fatigue

  • Mild fever

  • Difficulty breathing

  • Forward-leaning posture

  • Swelling in joints like ankles, heels, knees, and upper back

Symptoms in Women

how AS presents differently in females
While back pain is a primary feature for all genders, women often experience a distinct set of symptoms, leading to delays or misdiagnoses. Studies show that women may experience:

  • Intense fatigue

  • Longer morning stiffness

  • Reduced joint flexibility

  • More pain in the neck, knees, and hips

  • Higher rates of night pain and sleep disruption

Additionally, complications differ: women with AS are more likely to develop inflammatory bowel disease or psoriasis, while men are more prone to anterior uveitis.

When To Contact a Healthcare Provider

recognizing the need for medical help
If you notice persistent lower back pain or stiffness—especially in the morning—and it improves with movement, consider seeing a healthcare provider. Mention other symptoms like fatigue or joint pain. A healthcare professional may perform a physical exam and order imaging or blood tests, and possibly refer you to a rheumatologist for further evaluation.

A Quick Review

AS is an inflammatory arthritis that targets spinal joints and ligaments. It most often presents as lower back pain and stiffness but can also affect other joints and cause symptoms like fatigue and reduced flexibility. While AS is a lifelong condition, early diagnosis and appropriate treatment can significantly manage symptoms and slow its progression.