WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect: Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat. Signs of low sodium levels like headache, trouble focusing, memory problems, feeling confused, weakness, seizures, or change in balance. Signs of high blood pressure like very bad headache or dizziness, passing out, or change in eyesight. Upset stomach or throwing up. Hallucinations (seeing or hearing things that are not there). Feeling tired or weak. Restlessness. Muscle weakness. Muscle spasm. Not hungry. Shortness of breath, a big weight gain, or swelling in the arms or legs. Swelling, warmth, numbness, change of color, or pain in a leg or arm. Chest pain or pressure or a fast heartbeat. Coughing up blood. Weakness on 1 side of the body, trouble speaking or thinking, change in balance, drooping on one side of the face, or blurred eyesight. A heartbeat that does not feel normal.