Could lean kill you the first time you do it

First, it is not cool. In fact, it’s quite dangerous. Sizzurp, also known as "Lean" and "Purple Drank," is a mixture of cough medicine—often prescription strength, containing an opioid called codeine—and soft drinks and candy for flavor. Abuse of cough medicines, especially ones that contain opioids, can cause an overdose leading to coma or even death. Less grave (but still serious) symptoms include nausea, dizziness, impaired vision, memory loss, hallucinations, and seizures like Lil Wayne experienced.

Hair follicles, blood, etc.