Side effects of this medication are dry mouth, abdominal pain, nausea, vomiting, diarrhea, constipation, decreased appetite, weight loss, headache, dizziness, insomnia, increased blood pressure, irritability, and decreased libido. More serious side effects are blistering or peeling of the skin, confusion, fainting, irregular heartbeat, heart attack, stroke, severe allergic reaction, twitching, trembling, and hallucinations.