纳洛酮（Naloxone），又常以商品名「Narcan」贩售。该药物可以缓解摄入过量鸦片类药物所造成的影响。纳洛酮可以与鸦片类药物混入同一药品中，以减少误用时中毒的风险。纳洛酮常被制成鼻喷剂。若静脉注射给药，药效会于两分钟内作用；肌肉注射则约为五分钟内作用。纳洛酮的药效约会维持1至1.5小时左右，由于鸦片类药物作用的时间较纳洛酮长，因此在以纳洛酮进行治疗时必须多次给药。

在成瘾者戒断鸦片类药物的过程中，有些患者会出现戒断症。症状包含躁动、恶心、呕吐、心跳过快，和盗汗等等。因此可以在戒断初期每数分钟给予纳洛酮，直到其症状舒缓。有心脏病史的患者宜慎用该药物，因其可能会引发心脏疾病。孕妇在经过小规模人体测试后，目前显示没有不良影响。纳洛酮为一种竞争性受体拮抗剂，可与鸦片类药物竞争中枢神经和呼吸系统的受体，以舒缓症状。

Naloxone, sold under the brandname Narcan among others, is a medication used to block the effects of opioids, especially in overdose. Naloxone may be combined within the same pill as an opioid to decrease the risk of misuse. When given intravenously, it works within two minutes, and when injected into a muscle, it works within five minutes. The medication may also be used in the nose. The effects of naloxone last about half an hour to an hour. Multiple doses may be required, as the duration of action of most opioids is greater than that of naloxone.