Unresponsive or not breathing normally?Call 911 now

What are the signs of a fentanyl overdose?

Medically reviewed by Asia, RN, BSN

Written by Justin Alcalde, AHA and American Red Cross instructor, CPR West Covina

Price and class details checked .

Fentanyl is an opioid, so a fentanyl overdose shows the signs of any opioid overdose. The person cannot be woken up, and their breathing is slow, shallow or stopped. Other signs are very small pinpoint pupils, blue or purple lips and nails (on darker skin, a pale, gray or ashen look), choking, gurgling or snoring sounds, and a limp body. If you are not sure, CDC says to treat it like an overdose.

The best time to learn these signs is before you see them: our SOS First Aid app covers opioid emergencies in its BLS section, with practice quizzes to test what you remember.

The signs, one by one

SignWhat to look forWho lists it
Will not wake upDoes not respond when you shout their name, or when you rub firmly on the middle of their chest.CDC, SAMHSA, FDA Narcan label
BreathingSlow or shallow breathing, or none. Choking, gurgling or snoring sounds from someone who cannot be woken.CDC, SAMHSA, FDA Narcan label
PupilsVery small pinpoint pupils that do not react to light.CDC, SAMHSA, FDA Narcan label
Lips, nails and skinBlue or purple lips and fingernails. FDA also names the gums and fingertips. On darker skin, the skin may look pale, gray or ashen.CDC, SAMHSA, FDA
BodyA limp body. Cold or clammy skin.FDA, California Department of Public Health
HeartbeatA slow or irregular heartbeat or pulse.FDA
CDCSAMHSAFDA labelFDACDPH

Very high, or overdosing?

CDC says it may be hard to tell whether a person is high or having an overdose, and that if you are not sure, you should treat it like an overdose. The Narcan Drug Facts label describes a suspected overdose as a person who will not wake up, or is very sleepy, or is not breathing well. To check, it says to yell "Wake up!" and shake the person gently.

CDCFDA label
  • Call their name. If that does not work, SAMHSA says to rub your knuckles on the center of their chest or on their upper lip.
  • SAMHSA says that if you cannot wake them by shouting or by rubbing your knuckles on the breastbone, they may be unconscious.
  • Someone who is very sleepy and not breathing well already matches the label's description of a suspected overdose.
  • Watch the breathing most of all. SAMHSA says the goal is to restore breathing, and breathing is more important than waking up.
SAMHSAFDA label

Pinpoint pupils

The FDA patient information for Narcan describes pinpoint pupils this way: the black circle in the center of the colored part of the eye is very small, in someone who is difficult to wake. CDC adds that the pupils do not react to light. The same FDA information says to use Narcan right away if you think the signs of an opioid emergency are present, even if you are not sure, so there is no need to check every sign before you act.

FDA labelCDC

Skin color on darker skin

SAMHSA says that on lighter skin the skin tone may turn bluish purple, and on darker skin it may turn pale, grayish or ashen. CDC says to look especially at the nails and lips, and FDA lists blue lips, gums or fingertips among the signs.

SAMHSACDCFDA

What is different about fentanyl

  • It is strong. CDC says fentanyl is a synthetic opioid up to 50 times stronger than heroin and 100 times stronger than morphine, and that even small doses can be deadly.
  • It is often hidden. CDC says powdered fentanyl is mixed with heroin, cocaine and methamphetamine and made into pills that look like prescription opioids, and many people may not know their drugs contain it.
  • You cannot see, taste or smell it in other drugs, CDC says. SAMHSA says to use naloxone even if you are not sure what drugs someone took.
  • Naloxone works on it. SAMHSA says all opioid overdose reversal medications work on overdoses caused by fentanyl. How many doses it takes is where sources differ, below.
CDCSAMHSA

The xylazine catch

Xylazine, also called tranq, is a sedative that is not an opioid. CDC says it is being found in the illegal drug supply, is especially dangerous when combined with opioids like fentanyl, and can cause sedation, difficulty breathing, dangerously low blood pressure and a slowed heart rate. SAMHSA says a person who has taken xylazine may look like they are having an opioid overdose.

CDCSAMHSA
  • Give naloxone anyway. CDC says naloxone will not reverse xylazine, but because xylazine is often used with opioids like fentanyl, naloxone should still be given.
  • Call 911. CDC says the effects of xylazine may continue after naloxone is given.
  • Keep them breathing. If they do not respond to naloxone, SAMHSA says to keep giving rescue breaths until EMS arrive. CDC says first responders report that rescue breaths are especially helpful after xylazine.
CDCSAMHSA

Seeing these signs? Follow what to do if someone is overdosing for the full response, and how to use Narcan for the spray itself.

Where sources differ

Which signs each source lists. CDC and SAMHSA list four: not waking up, slow or shallow breathing, discolored lips and nails, and pinpoint pupils. FDA adds limpness and a slow or irregular heartbeat, and the California Department of Public Health adds a limp body and cold or clammy skin.

More than one dose for fentanyl. CDC says more than one dose of naloxone may be required when stronger opioids like fentanyl are involved. SAMHSA says more than one dose may not be necessary for a known fentanyl overdose, and that an overdose can seem to need extra doses when other sedating drugs, such as alcohol, benzodiazepines or xylazine, are also present.

Learn it before you need it

Start with our SOS First Aid app, built on the 2025 AHA guidelines: it puts each protocol in numbered steps and has an AI assistant you can ask about AED use, compression rates and more. Hands-on, we teach Heartsaver First Aid CPR AED ($98), Red Cross BLS ($69) and the $75 Red Cross Naloxone Skill Boost in West Covina, each of which its organization says covers opioid overdoses.

Questions people ask

Is snoring a sign of an overdose?

It can be. CDC lists choking sounds or a gurgling or snoring noise from a person who cannot be woken as a sign of overdose. If someone is snoring and you cannot wake them, treat it as an overdose.

Do pinpoint pupils always mean an overdose?

Not on their own. The FDA Narcan information lists very small pupils as a sign in someone who is difficult to wake, along with breathing problems. If the person cannot be woken or is not breathing well, act on that.

Can someone overdose on fentanyl without knowing they took it?

Yes. CDC says fentanyl is mixed into other drugs and pressed into pills that look like prescription opioids, that many people may not know their drugs contain it, and that you cannot see, taste or smell it.

What are the signs of xylazine in an overdose?

CDC says xylazine can cause sedation, difficulty breathing, dangerously low blood pressure, a slowed heart rate and wounds that can become infected. SAMHSA says it can look like an opioid overdose. Give naloxone anyway, call 911 and keep them breathing.

What should I do first if I see these signs?

Give naloxone if you have it and call 911, then help them breathe. Our guide to what to do if someone is overdosing walks through each step.

Related guides

Sources

This page is education, not medical or legal advice. In an emergency, call 911 first.