The toxicology and characteristics of fatal new psychoactive stimulant and hallucinogen-related poisonings in Australia, 2000-2025

New psychoactive stimulants and hallucinogens (NPSH) poisonings have generated considerable public health concern in recent years. We aimed to determine: 1. The characteristics, toxicology and major autopsy findings of known cases of NBZD-related poisoning in Australia, 2000-2025; and 2. Changes in characteristics of known cases from 2020 onwards compared to earlier known cases. Retrospective study of fatal NPSH-related poisonings in Australia retrieved from the National Coronial Information System. 70 cases were identified, the first occurring in 2007. In 22.9% the decedent appeared unaware they were consuming a NPHS, and in 32.9% the NPSH had been injected. The most commonly observed signs and symptoms of acute NPSH poisoning were intense agitation (22.9%), sudden collapse (22.9%) and hyperthermia (20.0%). There were 31 NPSH identified, of which 13 were first detected in the 2020 s. The most commonly detected NPSH were cathinones (48.6%), most frequently α-pyrrolidinovalerophenone and methylenedioxypyrovalerone. Phenethylamines were present in 38.6%, with paramethoxymethamphetamine and a range of the N-benzylphenethylamine series ( NBOMe) the most common. Tryptamines were present in 18.6%, and three cases involved piperazines. In 18 cases (25.7%) multiple NPSH were detected in the blood. 2020 s cases were more likely to have tryptamines detected (36.7 v 5.0%), but less likely to have phenethylamines (23.3 v 50.0%). Psychoactive drugs in addition to NPSH were present in 92.9%, most commonly psychostimulants (68.6%) and hypnosedatives (40.0%). A wider range of NPHS have been detected in recent fatal poisonings, with tryptamines becoming more common in the 2020 s, and phenethylamines less common. • 70 fatal toxicity cases involving new psychoactive stimulants/hallucinogens (NPSH) • 31 NPSH identified, of which 13 were first detected in the 2020 s • The most commonly detected NPSH were cathinones (48.6%) • In 18 cases (25.7%) multiple NPSH were detected in the blood • In 16 cases the decedent appeared unaware they were consuming a NPHS