This page is an ever-evolving FAQ, focusing on the most common questions I get about Narcan.

What is Narcan?

Naloxone hydrochloride is the chemical name of the primary component in the brand name product Narcan.

How does Narcan work?

Narcan is an opioid antagonist that works to temporarily block an opioid’s ability to reach receptors in the brain. If visuals work for you, picture Narcan as a headstrong child who doesn’t want anyone sitting in their chair. The child (Narcan) pushes the unwelcome visitor (opioids) out of the chair and occupies the space.

Is Narcan safe?

Narcan is absolutely safe. If a person receiving Narcan does not have opioids in their system, it will have no effect on them.

Does it hurt?

While Narcan is completely safe to use, it can cause the rapid onset of opioid withdrawal, which is anything but pleasant. This is why experienced and compassionate harm reductionists advocate only using Narcan if an individual is unconscious, non-responsive, and not breathing.

Will expired Narcan still work?

Yes! Several studies have shown that naloxone remains effective beyond its expiration date, despite being kept in suboptimal conditions. A particularly comprehensive study1 collected expired naloxone samples, some of which had expired in the early 1990s, from fire departments, emergency medical services, and law enforcement agencies. These samples, which had mostly been stored in ambulances, police cars, and similar environments, were tested and found to contain nearly all of their active ingredient, even after almost 30 years in storage. Only one sample, which had expired more than 25 years ago, had dropped to less than 90% of its original potency2.


1Schuyler Pruyn et al., Quality Assessment of Expired Naloxone Products from First-Responders’ Supplies, 23 Prehospital Emergency Care 5, 647-653 (2018),

2The potency of that sample, which expired in May 1992, was approximately 89% of that when it was new