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Healthcare providers may prescribe Narcan for a number of reasons, such as to reverse the effects of an opioid overdose, to help increase blood pressure in people with septic shock, or to diagnose a suspected opioid overdose. This medication comes as a liquid that is injected in a vein, muscle, or under the skin. Possible side effects may include nausea, vomiting, and sweating.


What Is Narcan?

Narcan® (naloxone hydrochloride) is a prescription medication known as a narcotic antagonist. It is approved for the following uses:
  • Reversing the effects of opioids, such as in cases of an opioid overdose or after surgery
  • Diagnosing a suspected opioid overdose
  • Helping to increase blood pressure in people with septic shock (life-threatening low blood pressure that results from a serious infection in the blood). 
(Click Narcan Uses for more information on this topic, including possible off-label uses.)

Who Makes This Medication?

Narcan was originally made by Endo Pharmaceuticals, Inc. Endo no longer makes brand-name Narcan, and it is no longer available. Generic versions are made by a couple of different manufacturers.

How Does Narcan Work?

It is not completely known how Narcan works. The drug is thought to work by competing with opioids for opioid receptors. Narcan binds to opioid receptors, but produces no effects. Instead, it prevents opioid medicines from also binding to the receptors, thus blocking their actions.
There are several types of opioid receptors located throughout the body. Narcan is thought to bind to mu, kappa, and sigma opioid receptors, but has its greatest effects on mu receptors.
The effects of Narcan may be shorter than those of some opioids. This means, in some cases, the drug may need to be given in repeated doses until the opioid medicine is no longer active in the body.
Written by/reviewed by:
Last reviewed by: Kristi Monson, PharmD;
Last updated/reviewed:
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