When is a doctor permitted to prescribe a medication for "off-label" use (an ailment for which the medication isn't officially approved)?

Using good judgment: There are no precise rules regarding this practice. Numerous drugs have been found to be helpful for conditions they were not originally intended for. Off-label prescribing is entirely legal & very common. Many doctors will reserve this practice for situations where other treatments have not been effective; there may be some small malpractice risk if the patient has an adverse effect. Best wishes

Case dependent: medicine is both a science and an art. there are times that a physician deems it appropriate to prescribe "off-label", dependent on an individual patient's symptoms and condition. always a good idea to educate yourself, and have a healthy rapport with your physician. communication is key with health maintenance/medication, and it is important to trust your physician's judgement and experience.