局部麻醉药（英语：local anesthetic）是指那些在人体的限定范围内能暂时完全地和可逆地阻断神经传导，即在意识未消失的状况下使人体的某一部分失去感觉，以便于外科手术进行的药物。普遍应用于口腔科、眼科、妇科和一些外科小手术中，用于暂时解除疼痛。局部麻醉药和全身麻醉药根本区别在于：局部麻醉药与神经膜上的钠离子信道上的某些特定部位结合后，通过钠离子信道的钠离子减少从而改变神经膜电位，导致神经冲动的传导被阻断，最终实现麻醉效果；而全身麻醉剂则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。

Local anesthetic (LA) is a medication that causes reversible absence of pain sensation, although other senses are often affected as well. Also, when it is used on specific nerve pathways (local anesthetic nerve block), paralysis (loss of muscle power) can be achieved as well.