Green’s Dictionary of Slang

1. (drugs) a slumped posture that follows the ingestion of heroin.

2012

‘Dutch’ ? (Pronounced Que) [ebook] ‘Fuck that, I’m a muhfuckin! Don,’ YaYa replied, going into a dope lean.

2. (US drugs) prescription cough syrup, containing codeine.

2001		UGK ‘Let Me See It’ 🎵 Sippin’ lean / Ain’t no thang of the past.
2008		N.Y. Times 11 Feb. 🌐 Prescription cough syrup — sometimes diluted, and often called ‘drank’ or ‘lean’ or ‘purp’ — is the recreational drug most closely associated with Houston’s fertile hip-hop scene.
2015		Guardian Rev. 13 Nov. 4/3: His ever-increasing appetite for ‘lean’ or ‘purple drank’. A mixture of prescription cough syrup containing promethazine and codeine.
2016		F. Stuart ‘Dispatches from the Rap Wars’ in chicagomag.com 🌐 He had been drinking a lot of lean—a mix of codeine cough syrup and soda—and smoking Scotty, as folks in Chicago refer to PCP, and he was really messed up.
2021		J. Fenton We Own This City 125: [He] moved from popping Percocets to taking Xanax bars and drinking ‘lean,’ a cough syrup mixture.
2021		Central Cee ‘Day in the Life’ 🎵 Everyone got PTSD, how come everyone now sip on lean?