Phenazolam (Clobromazolam): Emerging Designer Benzo, Toxicology & 2025–2026 U.S. Signal
What the evidence actually shows
Evidence Very LowDirect answer
Evidence review of phenazolam, often called clobromazolam online, covering Australian emergency detections, rising U.S. forensic prevalence, co-detection with opioids and other NPS, and major human-data gaps. Phenazolam is an emerging designer benzodiazepine commonly called clobromazolam in online markets and forums. Australian emergency toxicology detected clobromazolam frequently in a 2022–2023 cohort. Controlled human pharmacokinetic and dose-response data remain extremely limited.
Research brief
Questions this page answers
- Is clobromazolam the same as phenazolam?
- What is phenazolam?
- Is phenazolam replacing bromazolam?
- Has clobromazolam been found in overdose cases?
Signal
Scientific takeaways
- Phenazolam is an emerging designer benzodiazepine commonly called clobromazolam in online markets and forums.
- Australian emergency toxicology detected clobromazolam frequently in a 2022–2023 cohort.
- CFSRE reported rising phenazolam detections in U.S. blood specimens and drug materials during 2025.
- Phenazolam has been co-detected with opioids, novel opioids, stimulants, hallucinogens, and other benzodiazepines.
- Controlled human pharmacokinetic and dose-response data remain extremely limited.
Phenazolam (Clobromazolam): Emerging Designer Benzo, Toxicology & 2025–2026 U.S. Signal
Emerging-drug note: The name “clobromazolam” is widely used in online markets and forums, while forensic organizations increasingly use phenazolam. Product labels may not reliably establish identity.
Quick answer
Phenazolam is an emerging designer benzodiazepine often called clobromazolam online.
It is structurally similar to bromazolam with an additional chlorine substitution.
The compound is important because two independent surveillance systems have now documented real-world exposure:
- Australian emergency toxicology;
- U.S. forensic surveillance through CFSRE/NMS Labs.
Australian emergency-department signal
A 2024 Journal of Analytical Toxicology study reported clobromazolam detections in emergency-department intoxications in Victoria, Australia.
The compound was found in 100 of 993 cases in the reported cohort and was the most frequently detected designer benzodiazepine in that dataset.
That is a strong real-world exposure signal.
It does not establish the effects of clobromazolam alone because NPS intoxications often involve multiple substances.
Rising U.S. phenazolam detections
In December 2025, the Center for Forensic Science Research and Education issued a public alert describing rising phenazolam detections.
CFSRE reported phenazolam in:
- blood specimens;
- seized/drug material;
- U.S. and international cases.
The center noted increasing positivity during 2025.
Is phenazolam replacing bromazolam?
CFSRE explicitly highlighted phenazolam as a possible successor in a changing NPS benzodiazepine market as bromazolam faces tighter international control.
That does not mean every “bromazolam” product now contains phenazolam.
It means market surveillance is showing a shift worth monitoring.
Polysubstance detections
Phenazolam has been detected with:
- opioids;
- nitazene analogues;
- orphine opioids;
- medetomidine;
- stimulants;
- hallucinogens;
- bromazolam and other benzodiazepines.
That combination pattern is clinically important because a benzodiazepine may deepen sedation in an opioid-contaminated drug supply.
Effects and risks
Controlled human studies are lacking.
Based on benzodiazepine pharmacology and observed intoxication contexts, concerns include:
- sedation;
- amnesia;
- impaired coordination;
- disinhibition;
- loss of consciousness;
- dependence;
- withdrawal.
Why internet potency claims are premature
Phenazolam is new enough that online comparisons greatly outnumber controlled human studies.
Subjective reports cannot establish:
- exact potency;
- half-life;
- safe exposure;
- reliable equivalence with bromazolam or alprazolam.
Dependence, withdrawal, and evidence limits
Phenazolam/clobromazolam belongs in the designer-benzodiazepine safety framework even where compound-specific prospective studies are sparse. Benzodiazepine-type GABA-A modulation can produce sedation, impaired coordination, amnesia, tolerance, and physical dependence. With repeated exposure, abrupt cessation after dependence can produce severe withdrawal, including confusion or seizures. The precise timing cannot be inferred reliably from a seller label, a single toxicology report, or comparisons with bromazolam.
That distinction matters because designer-benzodiazepine names are easy to confuse and products may be mislabeled. A tablet advertised as one analogue may contain another benzodiazepine, multiple sedatives, or an opioid. Subjective effect alone cannot establish identity.
Interactions and overdose interpretation
Combining benzodiazepine-type depressants with opioids or alcohol can substantially increase sedation, loss of consciousness, aspiration, and respiratory compromise. In mixed-drug deaths, however, a detected benzodiazepine should not automatically be described as the sole cause. Forensic interpretation should consider co-detected opioids or other depressants, tolerance, specimen type, concentrations, and the circumstances of the case.
Testing
Routine immunoassays are designed around common benzodiazepines and metabolites and may not reliably identify every designer analogue. Confirmatory LC-MS/MS or high-resolution mass spectrometry with current reference data is more informative. A negative routine benzodiazepine screen cannot by itself rule out exposure to an unusual designer benzodiazepine.
The evidence-based takeaway is therefore narrower than an online potency ranking: phenazolam/clobromazolam is a real designer-benzodiazepine exposure concern, while exact human potency, duration, dependence incidence, and withdrawal timing remain insufficiently characterized for a consumer conversion chart.
Bottom line
Phenazolam/clobromazolam is one of the clearest examples of why an evidence database needs to track what is emerging now, not only historically famous RC benzos.
Australian clinical toxicology and U.S. forensic surveillance both show that the compound has moved into real-world drug markets.
The human pharmacology needed to define its risk precisely has not caught up.
Related evidence
Source ledger
References
2 sources
- 01Identification of clobromazolam in Australian emergency department intoxications using data-independent high-resolution mass spectrometry Emergency toxicology study · 2024PMID 38459915DOI 10.1093/jat/bkae012 PubMed →
- 02Novel Benzodiazepine Phenazolam Increasing In Detections and Prevalence Among U.S. Recreational Drug Markets Center for Forensic Science Research and Education · 2025 Source →