Reasonable medical necessity in California workers’ compensation means the medical treatment is appropriate, necessary to cure or relieve the effects of the work injury, and clearly related to that injury. It isn’t enough for care to be offered or requested; a treating physician must determine that the treatment is medically justified, supported by evidence, and aligned with standard care for the diagnosed condition. In practice, this often means the treatment has a reasonable chance of helping the worker recover or regain function and is appropriate given the injury, the patient’s overall health, and the expected benefits versus risks. Because of this, merely because an employee asks for a specific treatment does not automatically make it reasonable medical necessity. The decision rests on the physician’s medical judgment, the diagnosis, supporting medical evidence, and established guidelines or standards of care. Treatments that are experimental, not related to the injury, or not likely to provide meaningful benefit are typically not considered reasonable medical necessity, even if requested by the worker.