全身麻醉剂（英语：general anesthetics）是麻醉药中的一类。麻醉药根据作用部位的不同，可分为全身麻醉药（general anesthetics）和局部麻醉药（local anesthetics）。全身麻醉药作用于中枢神经系统，使其受到可逆性的抑制从而使得用户的意识、感觉特别是痛感消失，便于进行外科手术。全身麻醉药和局部麻醉药的根本区别在于，局部麻醉药与神经膜上的钠离子信道上的某些特定结合后，利用减少钠离子通过信道的方法改变神经膜电位，阻断神经冲动的传导；而全身麻醉剂的麻醉原理至今尚不十分明确。（可能是通过影响神经膜的物理性状，比如膜的流体性质、通透性等起到麻醉的作用）

A general anaesthetic (or anesthetic, see spelling differences) is a drug that has the ability to bring about a reversible loss of consciousness. Anaesthetists administer these drugs to induce or maintain general anaesthesia to facilitate surgery. Some of these drugs are also used in lower dosages for pain management. The biological mechanism(s) of the action of general anaesthetics are not well understood.