system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why haven't we been able to develop drugs that don't harm us?

There are a lot of things in life that make us happy; however, drugs can stimulate this feeling to reach a peak. Why haven't we been able to develop drugs like MDMA and cocaine that don't harm our bodies? Is it just not scientifically possible?
gpt
Drugs only have effects by making our bodies release or decrease chemicals that we already use on a daily basis. The problem is when you start messing with our natural systems it causes them to change. 

So for MDMA and cocaine they cause massive releases of chemicals in our brain that give us the stimulated euphoric feeling. The problem is they release so much that our bodies try to compensate by reducing out response to these drugs. After a while our bodies are so "turned down" that out normal day to day levels aren't enough and it becomes very difficult to feel good or even to feel normal without the massive doses the drugs are giving you. After time even the large releases from the drugs aren't enough and you have to take more and more. 


Drugs themselves are not necessarily dangerous but the problem come from changing the way our bodies function. So no there is not really a way to make a drug that will not alter out body chemistry.