Answer:
If you mean "Lean" as in the Sprite/Soda + Codeine/Cough Syrup drink
Explanation: It's dangerous because a small amount of codeine is converted to morphine in the body. Like morphine, codeine binds to receptors in the brain (opioid receptors) that are important for transmitting the sensation of pain throughout the body and brain. Thus drinking too much of it can lead to an overdose and kill you.
Side effects include: dizziness, sedation, nausea, and vomiting, drowsiness, dullness, lethargy, decreased physical and mental performance, anxiety, fear, dysphoria, change of character and physical dependence.
