Description
Benzodiazepines are a structural group of central nervous system depressants that are widely used in medicine as anticonvulsants, anxiolytics, hypnotics, sedatives, skeletal muscle relaxants and tranquilizers. Numerous benzodiazepines have been synthesized for use as pharmaceuticals and more than 40 have been placed under international control. However, many benzodiazepine-type NPS have also appeared in recent years, and often marketed in forms of presentation that are similar in appearance to legitimate medicines containing benzodiazepines. Significant variability in tablet strength and a range of polysubstance mixtures have been reported in falsified pharmaceutical tablets.
Common street names for benzodiazepines are Benzos, Blue bomb, Downers, Nerve pills or for example Canasson rouge.
Chemical structure
Benzodiazepines (BZDs) can be classified into eight sub-groups, based on their chemical structures: (i) 1,4-benzodiazepines, (ii) 1,5-benzodiazepines, (iii) imidazolobenzodiazepines, (iv) triazolbenzodiazepines, (v) 2,3-benzodiazepines, (vi) thienotriazolodiazepines, (vii) thienodiazepines, and (viii) oxazolodiazepines. More than 50 benzodiazepine-type NPS have been reported to UNODC. They primarily belong to these three sub-families: 1,4-benzodiazepines, triazolobenzodiazepines and thienotriazolobenzodiazepines (see Figure 1 and 2).
Figure 1: Chemical structures of five sub-families of benzodiazepines
Note: The structural differences between these families and the 1,4-benzodiazepine core are highlighted in red.
Source: UNODC, The challenge of New Psychoactive Substances - A technical update (United Nations publication, 2024).
Figure 2: Chemical structures of three further sub-families of benzodiazepines
Note: The structural differences between these families and the 1,4-benzodiazepine core are highlighted in red.
Source: UNODC, The challenge of New Psychoactive Substances - A technical update (United Nations publication, 2024).
Commonly used forms
Figure 3 shows commonly used forms of sedatives/hypnotics.
Figure 3: Sedatives and hypnotics commonly used forms
Source: UNODC, The challenge of New Psychoactive Substances - A technical update (United Nations publication, 2024).
Reported adverse effects
The depressant properties of benzodiazepines are derived from their effects on a combination of receptors in the GABA-A receptor complex in the brain. Primarily, the benzodiazepines enhance the action of the neurotransmitter gamma-aminobutyric (GABA) at the GABAA receptor to produce their sedative, hypnotic, anxiolytic, anticonvulsant and muscle relaxant effects.
On most substances that have emerged, there is limited pharmacological and toxicological information. However, there are reports that benzodiazepine-type NPS were not associated with greater acute clinical severity than pharmaceutical benzodiazepines. The use of benzodiazepines along with opiates or other central nervous system-depressant drugs highly increases the risk of overdose and death. Although deaths involving benzodiazepines may be under-reported, they are rare without the concurrent use of other drugs. Figure 4 shows reported effects of sedatives/hypnotics.
Figure 4: Reported effects of sedatives/hypnotics
Source: UNODC, The challenge of New Psychoactive Substances - A technical update (United Nations publication, 2024).
References
UNODC, The challenge of New Psychoactive Substances - A technical update (United Nations publication, 2024).
UNODC, Terminology and Information on Drugs, Third Edition (United Nations publication Sales No. E.16.XI.8)
UNODC, Early Warning Advisory on New Psychoactive Substances Dashboard, accessed 3 June 2026.
Blakey K, Thompson A, Matheson A, Griffiths A. What's in fake ‘Xanax’?: A dosage survey of designer benzodiazepines in counterfeit pharmaceutical tablets. Drug Test Anal. 2022;14(3):525-530. https://doi.org/10.1002/dta.3119
Smith JL, Jiranantakan T, Cullinan U, Ewers C, Roberts DM, Brown JA. Contents and Time-Course of Falsified Alprazolam Detections in New South Wales, Australia. Drug Alcohol Rev. 2025 Jul;44(5):1449-1458. https://doi.org/10.1111/dar.14068.
Greene S, Weber C, Lyons T, Schumann J, Hodgson S. Novel benzodiazepines in illicit drug use: sentinel emergency department data do not indicate disproportionate clinical harm. Int. J. Drug Policy. 2026, 105367. https://doi.org/10.1016/j.drugpo.2026.105367.
Last update: 03/06/2026