What Is Fentanyl? Potency, Overdose Signs, and What to Do

Fentanyl is a synthetic opioid. In a hospital it is a legitimate painkiller, used for surgery and severe cancer pain. On the street it is the drug behind most opioid overdose deaths in the United States, mainly because it gets pressed into counterfeit pills and mixed into heroin, cocaine, and methamphetamine without the buyer knowing.

The overdose section below is the one to know by heart.

What fentanyl is

Fentanyl was developed as a medical painkiller and is still prescribed as a patch, lozenge, or injection for people with severe pain, most often after surgery or in cancer care. The CDC puts its potency at 50 to 100 times that of morphine. Pharmaceutical fentanyl is tightly controlled and is not the main source of overdose deaths.

The fentanyl involved in most deaths is illegally made and sold as powder, as counterfeit pills stamped to look like oxycodone or Xanax, or mixed into other drugs. Because so little is needed to produce an effect, it is cheap to make and easy to cut into a supply. The amount in any given pill or bag is unpredictable.

Why potency matters

A small amount of fentanyl can be fatal to someone without opioid tolerance. People who think they are taking heroin, a pain pill, cocaine, or meth may be taking fentanyl. The CDC notes that powdered fentanyl looks like many other drugs and that many people have no idea their drugs contain it.

Tolerance also drops quickly after time away from opioids. Someone leaving detox, jail, or a treatment program is at higher risk of overdose if they use again at their old amount.

Overdose deaths, by the numbers

Illegally made fentanyl drove the third wave of the opioid crisis, which the CDC dates to 2013. In 2023, nearly 73,000 overdose deaths in the U.S. involved synthetic opioids other than methadone, mostly fentanyl. That was 69 percent of all overdose deaths that year. Deaths have fallen since then. The table shows the latest provisional counts.

Year	All drug overdose deaths (provisional)	Deaths involving opioids (provisional)
2024	81,313	55,296
2025	69,973	44,564

Source: CDC National Center for Health Statistics, provisional estimates released May 13, 2026. Provisional counts get revised as more death certificates are processed.

Signs of a fentanyl overdose

• Unconscious, or cannot be woken
• Slow, shallow, or stopped breathing, sometimes with choking, gurgling, or snoring sounds
• Blue, gray, or pale lips and fingernails
• Pinpoint pupils that do not react to light
• Limp body, cold or clammy skin

What to do if someone is overdosing

1. Call 911.
2. Give naloxone (Narcan or another brand) if you have it. Spray it into one nostril. If there is no response after 2 to 3 minutes, give a second dose.
3. Try to keep the person awake and breathing. If they are not breathing, give rescue breaths if you know how.
4. Lay them on their side so they do not choke if they vomit.
5. Stay until help arrives. The overdose can come back as naloxone wears off.

If you are not sure whether it is an overdose, treat it as one. Naloxone will not harm someone who has not taken opioids. These steps follow the CDC's overdose response guidance. Since March 2023 the FDA has allowed Narcan 4 mg nasal spray to be sold over the counter, so pharmacies and many community programs carry it without a prescription. Many states also have Good Samaritan laws that offer some protection from possession charges to the person who calls 911 during an overdose. What is covered varies by state.

Fentanyl test strips

Test strips detect fentanyl in a drug sample in about five minutes. They cannot tell you how much is present and they are not a guarantee, but they give people who use drugs a way to check a supply before using. Many syringe services programs and health departments hand them out free. The Sober Nation page on harm reduction covers test strips, naloxone, and syringe programs together.

Fentanyl addiction and withdrawal

Fentanyl produces dependence quickly, and withdrawal is rough: sweating, vomiting, diarrhea, muscle pain, anxiety, and cravings. Opioid withdrawal is rarely life threatening on its own, but it is miserable enough that most people cannot get through it alone, and the overdose risk afterward is real. A medically supervised detox can manage symptoms with medication.

The treatments with the strongest evidence for opioid addiction are the medications buprenorphine, methadone, and naltrexone, combined with counseling. Sober Nation's page on medication-assisted treatment explains how each works and how to find a prescriber. If you are not sure whether your own use has crossed a line, the opioid self-assessment is a place to start, and the signs of opioid addiction page goes through what to watch for.

Where to go from here

If the problem started with prescription pain pills, the guide to how to quit painkillers and the painkiller resources hub are written for that situation. If heroin is involved, getting sober from heroin deals with the fentanyl-contaminated supply directly. You can also search treatment centers by state in the directory. SAMHSA's National Helpline, 1-800-662-4357, is free, confidential, and answers around the clock.