Does Narcan Work on Fentanyl?

But because fentanyl is far more potent than most other opioids, using Narcan to reverse a fentanyl overdose often requires more doses and faster action. So, let’s take a closer look at why this is the case and how it works.

What Is Narcan? And How Does It Work?

Narcan is the most widely recognized brand name for naloxone, a medication that can reverse opioid overdoses. When someone takes an opioid—whether it’s a prescription painkiller, heroin, or fentanyl—the substance binds to opioid receptors in the brain and slows down the central nervous system. 

In an overdose, however, breathing slows to the point of stopping entirely. Yet, Narcan works by rapidly binding to those same receptors and displacing the opioid, which restores normal breathing within minutes.

It’s available in two main forms, a nasal spray and an injectable. In most U.S. states, you can walk into a pharmacy and purchase it without a prescription. It has no effect on people who haven’t taken opioids, which means there’s no risk in giving it to someone when you’re unsure what they’ve taken.

Can Narcan Reverse a Fentanyl Overdose?

Narcan can reverse a fentanyl overdose, but fentanyl creates a more complicated situation than most other opioids. The reason comes down to fentanyl's extreme potency and its behavior in the body. 

Unlike heroin or oxycodone, fentanyl is highly fat-soluble, meaning it distributes rapidly into body tissues and can keep releasing back into the bloodstream, continuously re-exposing opioid receptors. Narcan works the same way it always does, competing for those receptors, but the sheer amount of fentanyl cycling through the system means one dose is often not enough to hold the line.

How Many Doses of Narcan Does It Take for Fentanyl?

The number of doses needed depends on how much fentanyl was taken, whether other substances were involved, the person’s body weight and opioid tolerance, and the strength of the Narcan formulation being used.

Standard guidance is to administer one dose, then wait two to three minutes while monitoring for any sign of response, such as movement, breathing, or consciousness. If there is no change, give a second dose. 

In some fentanyl overdoses, three, four, or even more doses have been required before the person responded. Because of how common high-dose situations have become, higher-strength naloxone formulations like Kloxxado (8mg) were developed specifically with fentanyl in mind. If you carry Narcan, carry more than one dose. If you’re in a household where opioid use is a concern, having several on hand is a reasonable precaution.

How to Use Narcan Step by Step

If someone near you appears to be overdosing, such as being unresponsive, breathing very slowly or not at all, and their lips are turning blue, act immediately. Every second matters.

Here’s exactly what you should do:

1. Call 911 right away. Do this before anything else. Even if Narcan works, the person will need a medical evaluation.
2. Position the person safely. Lay them on their back on a flat surface.
3. Administer Narcan. For the nasal spray, insert the tip into one nostril and press the plunger firmly. For an injectable, follow the instructions included with the kit.
4. Perform rescue breathing if you are trained to do so. One breath every five seconds can help maintain oxygen levels while the Narcan takes effect.
5. Wait and watch. Give the Narcan two to three minutes to work. If there is no response, administer a second dose.
6. Once they are breathing, place them in the recovery position. Roll them onto their side to prevent choking if they vomit.
7. Do not leave. Stay with the person until emergency services arrive. Fentanyl can outlast Narcan, and a second wave of overdose is a real risk.

Where Can You Get Narcan?

Most major pharmacy chains, including CVS, Walgreens, and Walmart, carry it over the counter in states that allow dispensing without a prescription, which now includes the majority of the country. The cost varies, but manufacturer coupons and patient assistance programs can reduce or eliminate the price entirely.

For those who need it at no cost, community health organizations, harm reduction programs, and many local health departments distribute naloxone for free. Some areas also offer naloxone vending machines or community drop-off sites. 

Does Narcan Have Any Side Effects?

Narcan itself is actually a fairly safe medication. As previously mentioned, in someone who has not taken opioids, it produces no noticeable effect whatsoever. There is no high, no sedation, and no physical reaction. This is why it can be administered freely when there is any doubt about what someone has taken.

In someone who is physically dependent on opioids, however, Narcan triggers sudden withdrawal. Because it blocks opioid receptors so quickly, the body is abruptly deprived of the substance it has adapted to. This can cause agitation, nausea, vomiting, sweating, rapid heart rate, and intense cravings. And yes, it’s really uncomfortable; the person may be disoriented or even combative when they regain consciousness. 

Ultimately, Narcan is one of the most important tools available in the fight against the opioid crisis, and knowing how to use it is genuinely life-saving knowledge.  If someone in your life has needed Narcan, however, this is a sign that they need more than emergency intervention. Real, lasting recovery is possible with the right treatment and support behind it. 

At Freedom Recovery Centers (FRC) in Richmond, Virginia, we work with people navigating opioid addiction every day, including those whose lives have been shaped by fentanyl. If you’re ready to explore what treatment may look like for you or a loved one, call us at 804-635-3746 or reach out through our online contact form. A conversation costs nothing, but it has the potential to change everything.