Drugs can cause psychoactive dependance, which means that you become an addict. Once addicted you can't pass a day without it. It is also illegal to even posses drugs. The effect of this on children is great because children have a very big sense of curiousity thus, it causes them to try it. And eventually they too become an addict. Another is that you earn a lot of money through drug trade. So if a child or even a teen gets influenced he or she may become a criminal or a drug pusher. Drugs have many effects on us and all humans.