The first signs of AS are pain and stiffness in the lower back. This is especially bad in the morning on getting up. This is quite different from back strain which is better with rest. Occasionally, this may be associated with pain in the hips and knees. 

As the condition progresses, the pain and stiffness can affect the entire spine and last the whole day. This causes difficulty in walking, getting out of bed, bending forward and other activities of daily living. Patients with active AS often experience fatigue, poor appetite and weight loss. Occasionally, the eyes can also be affected in AS and the symptoms include redness of the eyes, increased sensitivity to light and blurred vision.