Dynastat must not be used in patients with:  a history of serious allergic reactions to medicines, especially skin reactions;  stomach ulcers or bleeding in the stomach or gut;  allergic-type reactions such as asthma, cold-like symptoms, polyps in the nose, swelling of the face or hives after taking aspirin or NSAIDs, including other COX-2 inhibitors;  severe liver disease;  inflammatory bowel disease;  heart failure (an inability of the heart to pump enough blood around the body), heart disease, peripheral artery disease (obstruction of the arteries in the arms or legs), or cerebrovascular disease (problems affecting the blood vessels in the brain).