Green’s Dictionary of Slang

(drugs) Benzodiazepine, merchandised as diazepam (Valium), lorazepam (Ativan), etc.

1988		Sydney Morn. Herald 21 Feb. 19/2: ‘The thing is about benzos (the benzodiazepene minor tranquillisers) is that they don’t do anything for me, they just stop fits or barbituate withdrawal,’ she said.
1994		T. Willocks Green River Rising 198: There’s some real goof shit fo’ y’all yonder [...] Benzos, barbs, codeine.
1996–2003		urban75 Urban75.com 🌐 Benzodiazepines (Benzos, temazies, jellies, eggs, moggies, vallies).
1999		D. Looser ‘Boob Jargon’ in NZEJ 13 27: benzon. Benzedrine piU (amphetamine).
2000		G.V. Higgins At End of Day (2001) 31: He’s sellin’ benzos for two bucks a pill.
2011		R. Goodwin ‘Threshold Woman’ in Pulp Ink [ebook] ‘Someone’s taken too much acid. I need you to help them come down.’ [...] ‘She needs a benzo like Klonopin’.
2018		G. Gilmore Base Nature [ebook] ‘Benzos’, or ‘benzodiazepine receptor agonists’ were, apparently, commonly found in sleeping tablets.
2021		T. Swerdlow Straight Dope [ebook] I was half dead on benzos and blood pressure medicine.