Some patients that take Trileptal may experience side effects ranging from mild to severe. An allergic reaction may occur with use of the drug and will be characterized by a patient developing a swelling in the facial region, hives, or a difficulty breathing. Some minor adverse reactions include the following symptoms: mild nausea, stomach pain, slurred speech, lack of coordination, blurred vision, difficulty maintaining mental acuity, shaking, drowsiness, skin rashes, diarrhea, or vomiting. Severe side effects include seizures, a decrease in urination, abnormal bleeding or bruising, weakness, swollen glands, jaundice, and severe skin rashes. In addition, Trileptal may cause thoughts of suicide in some users. These major adverse reactions should be reported to medical personnel immediately.