system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: What actually causes death from an overdose?

The airway obstruction and respiratory distress are obvious killers but, people still die even when that is mitigated. Is there something happening at different levels that causes death?
gpt
Overdose on what? Different substances have very different effects on the body. 

Opioid toxicity is when the drugs effect the parts of the brain that control your breathing, it can literally slow your breathing to the point you’re not gettin enough oxygen in your system. You suffocate from it but not because of any blockage or restrictions, you simply stop breathing to put it simply. 

Cocaine on the other hand is a stimulant so it can increase your heart rate or blood pressure to the point of causing a heart attack or stroke. 

Each drug has it’s own pathology when it comes to overdosing.