Are all illegal drugs harmful? If not, why are they prohibited?

Question: Are all illegal drugs harmful? If not, why are they prohibited?
- Keywords:
  ethical,
  illegal substance,
  medicine
Asked by to Daryl on 24 Jun 2014. This question was also asked by .
- Daryl Jones answered on 24 Jun 2014:
  
  Yes they are very harmful!! They can kill people very quickly!
  Some are so harmful that they can kill you the very first time you try them

Question: Are all illegal drugs harmful? If not, why are they prohibited?