Continuous methysergide administration should not exceed six months without a drug-free interval of at least one month for re-assessment; dosage should be reduced gradually over two to three weeks to avoid rebound headaches. In patients undergoing treatment with methysergide, dose of ergotamine required to control acute attacks may have to be reduced. Particular attention should be paid to complaints of urinary dysfunction, pain in loin, flank or chest, and pain, coldness or numbness in limbs. Patients should be regularly examined for presence of cardiac murmurs, vascular bruits, pleural or pericardial friction rubs and abdominal or flank masses or tenderness. Caution also advised during drug administration in past history of peptic ulceration. At first signs of impaired peripheral circulation, prompt withdrawal of drug recommended. In carcinoid syndrome, risk of adverse reactions due to higher dosage must be weighed against therapeutic benefit. Patients might experience side effects such as dizziness, drowsiness or disturbances in vision.