ADVERSE REACTIONS The most frequently observed adverse reactions include lightheadedness, dizziness, sedation, shortness of breath, nausea and vomiting. These effects seem to be more prominent in ambulatory than in non-ambulatory patients, and some of these adverse reactions may be alleviated if the patient lies down. Other adverse reactions include allergic reactions, euphoria, dysphoria, constipation, abdominal pain and pruritus. At higher doses codeine has most of the disadvantages of morphine including respiratory depression. The most common adverse reactions associated with the use of aspirin have been gastrointestinal, including nausea, vomiting, gastritis, occult bleeding, constipation and diarrhea. Gastric erosion, angioedema, asthma, rash, pruritus and urticaria have been reported less commonly. Tinnitus is a sign of high serum salicylate levels (see OVERDOSAGE ). Aspirin Intolerance: Allergic type reactions in aspirin-sensitive individuals may involve the respiratory tract or the skin. Symptoms of the former range from rhinorrhea and shortness of breath to severe asthma, and the latter may consist of urticaria, edema, rash or angioedema (giant hives). These may occur independently or in combination.