Purple drank – aka lean, drank and other names – is a slang term for prescription cough syrup and soft drink. Most often made with cough syrup containing codeine and promethazine, drank can also be made with over-the-counter cough syrup made with dextromethorphan.
Codeine is an opioid, and thus habit-forming. Although not particularly potent, codeine can be lethal if too much is taken, or if the drug is taken with other drugs such as alcohol. Codeine abuse is a serious medical issue and should be treated at a detox center.