What is ISO? Illicit Drugs and Opioid Overdose

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The new year is here, and one thing that means is that it’s time to examine the confirmed and verified data from 2022 and 2023: this year, among other things, the presence of a new drug called ISO is causing serious problems among people who use illicit drugs, exacerbating the opioid crisis, and adding a new element to the ongoing effort to mitigate the harm caused by drug addiction and overdose.

In this article, we’ll talk about a new drug involved in opioid overdose deaths – ISO – and address the problem of polysubstance misuse. We’ll also talk about how a new generation of designer drugs complicates the efforts of policymakers, treatment providers, and community advocates to help people with substance use disorder (SUD).

What is ISO?

ISO is short for “Isotonitazene,” which is a synthetic opioid recently identified by the Drug Enforcement Agency (DEA) as an emerging threat in the United States. Isotonitazene is one of a class of powerful opioid drugs developed in the 1950s called nitazenes. Here’s how the DEA describes nitazenes:

“Nitazenes are dangerous synthetic opioids that can be as powerful, or even more powerful, than fentanyl. They have no legitimate use.”

To learn more about nitazenes, please navigate to the blog section of our website and read this article:

Nitazenes: A New Factor in the Opioid Crisis

Experts indicate that nitazenes can be up to 10 times as potent as fentanyl, which itself is 50 times more powerful than heroin. That’s why ISO is so dangerous, and that’s why representatives from the DEA warn that ISO may exacerbate the overdose crisis in the U.S.

Designer Molecules Like ISO and Drug Overdose

People familiar with the phrase designer drugs often think of party drugs such as MDMA (ecstasy) popularized during the 1980s and 1990s, associated with all-night dance clubs, alternative lifestyles, the rave culture. What many people don’t know is that the culture of all-night partying and dance parties – with the assistance of various illicit drugs – never went away. In the 80s and 90s – and now – it’s common to mix opioids, stimulants, amphetamines, and alcohol in an ad hoc cocktail designed to reduce inhibitions, increase feelings of connectedness (I love everyone!), induce euphoria, and give people the energy to stay up all night.

That’s a somewhat romantic – and unrealistic – view of designer drugs. It’s particularly off base when we consider the new generation of designer drugs such as fentanyl, carfentanil, xylazine, and nitazenes. There’s nothing fun or party-like about these drugs or their consequences. They do two primary things:

  1. Increase profits for drug traffickers
  2. Increase risk of overdose and death for people who take them

When we talk about the opioid crisis, we logically focus on opioids. However, since the mid-teens – around 2015 – the opioid crisis has grown complicated, and although opioids are the main driver of the opioid crisis, fatal overdose involving other drugs is part of why the crisis persists.

This is where it gets more complicated. The other drugs contributing to the overdose crisis, such as methamphetamine, amphetamine, and cocaine, are now likely to contain drugs such as fentanyl, carfentanil, xylazine, and nitazenes.

ISO, Fentanyl, and Overdose

Why do drug traffickers put fentanyl and nitazenes in drugs like methamphetamine and others?

First, it’s currently easy for cartels – such as the Sinaloa Cartel and the Jalisco cartel – to buy the chemical precursors to fentanyl from overseas suppliers. It’s also not hard or too complicated to manufacture fentanyl or nitazenes in illicit laboratories. After manufacture, traffickers mix these chemicals – which they create themselves, and are easier to source than the opium or coca necessary to manufacture heroin or cocaine – with their supply of illicit drugs, which increases volume, thereby increasing their profit, as we mention above.

That’s good for drug traffickers, but a literal recipe for disaster for people who use drugs, especially people who use illicit opioids, illicit/fake prescription medications, methamphetamine, stimulants, or tranquilizers like benzodiazepines.

Here’s the problem, or part of it: a person who uses opioids often understands the warning signs of opioid overdose – and they often also have Narcan on hand in case of an accidental overdose. However, a person who takes an illicit stimulant, like cocaine, or an amphetamine, like methamphetamine, might not be on the lookout for the signs of opioid overdose, since stimulants/amphetamines generally have the opposite effect of opioids.

In other words, they may not know to watch for the warning signs of opioid overdose.


Because they had no idea they ingested and opioid or opioid-derived medication like fentanyl or a nitazenes like ISO.

Highest Danger: Illicit Opioids, Methamphetamine, Fake Prescription Drugs

Drugs like fentanyl, xylazine, and ISO – a.k.a. nitazenes – make purchasing illicit drugs akin to playing Russian Roulette. Here’s how DEA intelligence analyst Maura Gaffney describes the problem:

“People have to keep in mind, with all the synthetic drugs out there, and the way they’re being mixed together, you never know what you’re actually buying.”

In 2021, over 108,000 people died of drug overdose, with 75 percent of those fatalities involving a synthetic opioid. And, as we mentioned above, in many cases, overdose victims never knew they ingested an opioid.

According to the DEA, synthetic opioids – the new, deadlier designer drugs – are now detected in a variety of illicit and fake prescription drugs:

  • Amphetamine
  • Methamphetamine
  • Cocaine
  • Heroin
  • Benzodiazepines
  • Prescription opioids

Warning signs of a fentanyl or designer opioid overdose include:

  • Person is unresponsive
  • Irregular breathing
  • Gray, pale, bluish skin/lips
  • Tiny, pinpoint pupils

If you see these signs in someone, take the following steps:

  1. Call 911
  2. Administer Narcan, if it’s on hand
  3. Administer CPR, if you know it
  4. If nothing changes, administer a second dose of Narcan
  5. Stay with overdose victim until help arrives

At the moment, there is no way for a regular person to test for or detect ISO in an opioid or another drug. However, fentanyl test strips are readily available and easy to use. To learn more about fentanyl test strips, check the Centers for Disease Control Fentanyl Test Strip Page. Buying fentanyl test strips is easy: simply search ‘fentanyl test strip’ on Amazon. To find free fentanyl test strips in your area, please visit the National Harm Reduction Coalition Fentanyl Page.

The materials provided on the Pinnacle Blog are for information and educational purposes only. No behavioral health or any other professional services are provided through the Blog and the information obtained through the Blog is not a substitute for consultation with a qualified health professional. If you are in need of medical or behavioral health treatment, please contact a qualified health professional directly, and if you are in need of emergency help, please go to your nearest emergency room or dial 911.