Are "off-labels" legal?

A doctor prescribes a beta-blocker to calm a patient's muscle tremors, even though the Food and Drug Administration (FDA) has only approved the drug for use in lowering blood pressure. A physician recommends that a patient wear a nicotine patch as a treatment for colitis. A pediatrician prescribes a drug that has been approved for adult use only. Such "off-label" prescriptions are increasingly common--and legal.