Patients with ankylosing spondylitis (AS) are often prescribed nonsteroidal anti-inflammatory drugs (NSAIDs). These medications have a tendency to irritate the gastrointestinal (GI) system and make peptic ulcers worse. They can also increase the risk for GI bleeding. These concerns should be discussed with your doctor. 

Other medical conditions commonly associated with AS include ulcerative colitis and Chron's disease. Again, these should be discussed with your family doctor. Your orthopedic doctor usually doesn't treat these conditions.