Some patients who take AGGRENOX may experience side effects. The most common side effects of include headache, upset stomach, and diarrhea. Because AGGRENOX contains aspirin, the risk of bleeding is increased and it may take longer to stop bleeding. AGGRENOX may cause serious side effects such as: Severe headache with drowsiness, Confusion or memory change, Passing out (becoming unconscious), Bleeding in your stomach or intestine, Stomach pain, Heartburn or nausea, Vomiting blood or vomit that looks like "coffee grounds", Red or bloody stools, Black stools that look like tar, New or worsening chest pain in some people with heart disease, Liver problems, Loss of appetite, Pale-colored stool, Stomach-area (abdominal) pain, Yellowing of your skin or whites of your eyes, Dark urine, Itching This is not a complete list of side effects and others may occur. Call your doctor for medical advice about additional side effects that you may experience.