Side effects Headache, Dizziness, Upset stomach, Flushing, Fatigue, Nervousness, Angina, Flushing, Hypotension, Hypertension, Palpitations, Ventricular arrhythmia, Premature ventricular contractions, Adams-stokes syndrome, Bradycardia (with tilt table testing), Dyspnea, Edema, Blurred vision, Headache, Dizziness, Nervousness, Restlessness, Seizures, Nausea, Vomiting, Hypokalemia, Increased serum glucose, Tremor, Weakness