Don't do drugs

They're bad for you

What drugs do to your brain.

Over use or any use of drugs can cause a permanent and maybe fatal chemical imbalance. Typically what happens is that the drug molecules affect the receptors in the brain that take part in signal transmission between brain cells. What usually happens is that one cell sends a signal to another cell by releasing chemicals neurotransmitters that travel across a gap synapse between the two cells. The receiving cell then detects the neurotransmitters because they bind to receptors on the cell surface, and that binding generates a change in the receptor cell - which responds in whatever way "message received" triggers. Drugs may block reception of neurotransmitters, or stimulate random generation of signals at the wrong time, and so forth. The details are going be different depending on the drug otherwise they'd all seem to have the same effect, that's the general idea on the situation.