Naloxone reversed suspected synthetic cannabinoid overdose despite negative opioid tests | Research

The takeaway

A patient with suspected K2/spice overdose showing mental status changes and respiratory depression repeatedly improved with intranasal naloxone despite negative toxicology screens for both opioids and known synthetic cannabinoids, suggesting either opioid contamination or cannabinoid-opioid receptor crosstalk.

Emergency medicine providers, harm reduction workers, and anyone concerned about synthetic cannabinoid safety.

Patient improved with naloxone despite negative screens for both opioids and synthetic cannabinoids

What the researchers found

A 43-year-old man with schizoaffective disorder presented with altered mental status and respiratory depression after suspected K2 use. He improved with intranasal naloxone despite negative opioid and synthetic cannabinoid screens. He later admitted ongoing K2 use. The clinical response suggests either opioid adulteration of the K2 or functional interactions between CB1 and opioid receptors.

Why it matters

Synthetic cannabinoid products are increasingly contaminated with opioids, and standard toxicology screens cannot detect most novel synthetic cannabinoids. This case demonstrates that naloxone should be considered in undifferentiated overdoses even without confirmed opioid exposure, given its safety profile and potential effectiveness.

The numbers in context

One patient, age 43, with schizoaffective disorder and polysubstance dependence. Repeated improvement with intranasal naloxone. Negative toxicology for opioids and known SCRAs. Preclinical evidence supports CB1-opioid receptor crosstalk as a possible mechanism.

How the study worked

Case report with literature review. Standard toxicology screens for opioids and known synthetic cannabinoids were negative. Clinical response to naloxone was documented across episodes. A unit search found leafy substances, but confirmatory testing was negative due to the constantly changing chemical composition of synthetic cannabinoids.

What this study cannot tell us

Single case report cannot establish causation. The mechanism (opioid contamination vs CB1-opioid crosstalk) remains uncertain. Negative toxicology could mean either no opioids were present or the specific opioid was undetectable by standard screens. Concurrent medications and schizoaffective disorder complicate interpretation.

How to read the evidence

Single case report with literature review, providing clinical observation but no controlled evidence.

When this study was published

Published in 2025.

The bigger picture

The inability of standard tests to detect novel synthetic cannabinoids is a growing crisis. The street drug supply is increasingly contaminated with fentanyl and other opioids, meaning that what users think is a cannabinoid product may contain lethal opioid doses. Naloxone's safety makes it a reasonable intervention even when the diagnosis is uncertain.

Questions still open

How common is opioid contamination of synthetic cannabinoid products? Does CB1-opioid receptor crosstalk have clinical significance beyond this case? Should naloxone be routinely administered in suspected synthetic cannabinoid overdoses?

Common questions

Why didn't the drug test detect K2?

Synthetic cannabinoid manufacturers constantly change their chemical formulas to evade both legal bans and drug tests. Standard screens only detect previously identified compounds, so novel SCRAs go undetected.

Could the K2 have been laced with opioids?

This is one possibility. Fentanyl and other opioids are increasingly found in the street drug supply, including products sold as synthetic cannabinoids. The negative opioid screen does not rule this out, as novel opioid analogs may also evade detection.

Read the original research

Intranasal naloxone to treat suspected synthetic cannabinoid overdose: A case report and literature review.

The mental health clinician, 15(5), 248-251

View on PubMed ↗Publisher’s paper ↗

Citation

Dickinson, Jaden; Buckley, Tiffany. (2025). Intranasal naloxone to treat suspected synthetic cannabinoid overdose: A case report and literature review.. The mental health clinician, 15(5), 248-251. https://doi.org/10.9740/mhc.2025.10.248