This Week’s Focus: Ketamine & Fentanyl

Our focus for this week’s NDEWS Weekly Briefing is on the trends of non-medical use, detection, and the risks associated with overdoses involving the co-use of ketamine and fentanyl.

Our NDEWS Early Warning Network was alerted by a member of the Alberta Law Enforcement Response Team to a concerning trend found in the Alberta, Canada drug supply. It was reported that there is an increase in the prevalence of ketamine in law enforcement-seized drugs and that ketamine is being identified in fentanyl mixtures.  

This briefing highlights recent literature on these two substances as well as our biospatial.io report and web monitoring report. It is important to pass these early signals and information along to our community so that harm reduction can be evaluated to develop a response. We will continue to monitor these trends over time.  

Out of 3,163 EMS encounters for overdoses involving both ketamine and fentanyl from January 2022 to June 2025, 950 (30.0%) occurred in Western states, 1,228 (38.8%) in Central states and 985 (31.2%) in Eastern states. The data shows a statistically significant increase in EMS encounters for overdoses involving both ketamine and fentanyl across Eastern and Western states, and nationally overall. The trend is not significant (i.e., no statistically significant increase or decrease) for Central states.

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Why are we reporting on this? In response to feedback to our NDEWS Early Warning Network, a reader alerted us to a potential trend in the combined use of ketamine and fentanyl. Recent Reddit discussions highlight growing concerns about fentanyl contamination in ketamine supplies and fatal overdoses from this combination at festivals and in recreational settings.

What are ketamine and fentanyl? Ketamine is a dissociative anesthetic used medically for anesthesia and depression treatment, but recreationally produces hallucinogenic effects, out-of-body experiences, and sedation. Fentanyl is a potent synthetic opioid approximately 50-100 times stronger than morphine, used medically for severe pain but increasingly found contaminating illicit drug supplies.

Public health impacts: Reddit discussants report being around fatal overdoses from ketamine contaminated with fentanyl, particularly at music festivals. Commenters express difficulty identifying contamination through appearance or effects alone, creating uncertainty about substance purity.

How is it being discussed? Festival safety dominates conversations, with Reddit users sharing reports of deaths at UK festivals allegedly linked to fentanyl-contaminated ketamine. Testing practices receive significant attention, with users recommending multiple reagent tests and fentanyl test strips, though some report challenges with testing ketamine specifically.

Several discussants report using ketamine to manage opioid withdrawal symptoms or as part of polysubstance use patterns. Post creators frequently seek advice on identifying pure ketamine through visual inspection, taste, or effects, though experienced users emphasize testing as the only reliable method.

Medical interactions concern some commentors, particularly those on antidepressants or with pre-existing conditions. Discussants share varied experiences with combining ketamine and opioids intentionally, with some reporting enhanced euphoria while others describe dangerous respiratory depression. Naloxone (Narcan) effectiveness for ketamine-related overdoses generates confusion, with some commenters clarifying it only reverses opioid effects, not ketamine toxicity.

Search method: The web monitoring team started with 16 ketamine terms that have been used online, and 18 fentanyl terms that have been used online. The web monitoring team searched for any instances where at least one term from the ketamine list and at least one term from the fentanyl list were mentioned, with 288 potential starting name combinations. After filtering for terms used more than five times in the past year and a half, and for term combinations which almost exclusively referred to ketamine and fentanyl respectively as opposed to other substances, the team was left with six ketamine terms and four fentanyl terms for a 24 potential name combinations.

Here are the lists of finalized terms for each:
Ketamine: Ketamine, Special K, Ket, Horse tranquilizer, Wonky, K-hole
Fentanyl: Fentanyl, Fent, Fetty, Dirty 30s

Click here to read more about NDEWS Online Monitoring.

A recently published study in Drug and Alcohol Dependence by Delcher et al. including NDEWS Co-Investigator Bruce Goldberger, NDEWS SAG Member Agnes Winokur, and NDEWS contributors Arjun Iyer and Trokon Johnson, examined recent surveillance signals that suggest Florida is experiencing a resurgence in carfentanil-involved deaths. Data from the Florida medical examiner’s office were analyzed from 2016-2023 in addition to six state and national data sources. They found 24 carfentanil-involved deaths in a 2-month period (Nov/Dec 2023). Compared to 2017, decedents had increased exposure to fentanyl from 23.4% to 68.8%, p<.0001 and methamphetamine from 8.5% to 20.4%, p=0.0003. Read the article here.

A recently published Viewpoint in JAMA Internal Medicine by Zhu et al. including NDEWS Co-Director Joseph Palamar and SAG member Alex Krotulski describes BTMPS' spread across the US, explore key hypotheses for its rapid emergence, assess potential health risk, and outline ongoing public health response needs. BTMPS was first detected in fentanyl samples in June 2024 by drug checking programs in Portland, Oregon and was detected in nearly every state by September 2024. The role of BTMPS in the fentanyl supply remains unclear and the health risks associated are limited as BTMPS is not approved for human consumption. The authors emphasize the need for stronger public health surveillance. Read the article here.

A recently published article in Psychology Today's Addiction Outlook by NDEWS SAG member Mark Gold features research by NDEWS Director Linda Cottler and Co-Director Joseph Palamar and discusses the rise of non-prescribed ketamine use and misuse and the harms associated. The article also outlines criteria for identifying "ketamine use disorder". Read the article here.

A recently published editorial in Addiction by Bowden-Jones et al. discusses the balance of benefits and harms associated with ketamine in medical and non-medical use settings. The editorial noted that the non-medical use of ketamine is increasing, and global seizures have reached record levels. Reported harms from persistent non-medical use of ketamine, particularly at higher doses, include psychological dependence, cognitive impairment, hepatotoxicity related to biliary obstruction and choledochal cysts. The most long-term harm relates to ketamine-related urinary tract damage. Read the editorial here.

A recently published review in Journal of Substance Use and Addiction Treatment by Janssen-Aguilar et al. evaluated ketamine’s potential for treating Alcohol Use Disorder, Cocaine Use Disorder, Opioid Use Disorder and Cannabis Use Disorder. The review surveyed three databases that included 14 studies, published between 2002 and 2023, and 551 participants and the results of the included studies demonstrated ketamine’s efficacy across the aforementioned Substance Use Disorders. Read the review here.

Recently published to the American Addiction Centers website by Geoffrion et al. discussed the dangers presented by fentanyl and mixing it with various other drugs such as: opioids, benzodiazepines, alcohol, ketamine, MDMA, cocaine and methamphetamine. It was referenced that the combination of ketamine and opioids like fentanyl could cause potentially life-threatening respiratory depression as well as other adverse symptoms, such as oversedation. Read more here.

The Overdose Prevention Strategies website was submitted to NDEWS by National Association of Drug Diversion Investigators, Inc. (NADDI) Chief Operating Officer and NDEWS Community-Based Health Expert Lisa McElhaney. Created by NADDI, the website is an evolving resource that provides a centralized location for our nations overdose prevention efforts.  The primary focus is on the existing programs, laws, and resources of each individual state as they combat the substance abuse problem within their communities.

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The Weekly Briefing is a newsletter published each week by the National Drug Early Warning System (NDEWS) Coordinating Center, which is funded by the National Institute on Drug Abuse (U01DA051126) to the University of Florida (MPI: Cottler (contact), Co-Is: Goldberger, Nixon, Striley), NYU Langone Health (MPI: Palamar), and Florida Atlantic University (Co-I: Barenholtz). Any item may be reproduced provided the source is acknowledged.