Oxycodone
People can die from overdosing on oxycodone (taking too much).  Too much oxycodone shuts down the part of the brain that tells us to breathe.  This can cause respiratory failure - where the body is not getting enough oxygen to survive.  Every part of the body needs oxygen to live, and without enough oxygen, parts of the body - like the brain - will start to die.  Eventually, a person's breathing can stop.  If they do not get help right away, their heart will stop and they will die.