What is naloxone (Narcan®️, Evzio®️)?


Naloxone is an opioid antagonist used to rapidly reverse the effects of an opioid overdose. While not directly used to treat OUD, it is an essential emergency medication that saves lives in overdose situations. It can be administered by medical professionals or by laypersons with minimal training.

Historical context

Naloxone was first synthesized in 1961 and gained FDA approval in the United States in 1971. It has become increasingly available to the general public in recent years, with many pharmacies providing it without a prescription and numerous community-based programs distributing it to individuals at risk of opioid overdose.

Medical formulations

Naloxone is available as injectable solutions, auto-injectors, and nasal sprays (e.g., Narcan®️ Nasal Spray, Evzio®️ auto-injector).

How long does naloxone stay in your system?

Naloxone has a half-life of approximately 1 to 1.5 hours. It takes roughly 5 to 7.5 hours for the drug to be completely eliminated from the body.

Street names

Narcan, Nalox, Nalo


Naloxone injectable solutions are typically clear and colorless. Narcan®️ Nasal Spray comes in a pre-filled, single-use device with a protective cap, while the Evzio®️ auto-injector is a small, portable device with voice instructions for administration.

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