What's the difference between やく and くすり?


They both mean medicine. But when to use which?




According to [this dictionary entry](https://www.weblio.jp/content/%E8%96%AC)
薬{くすり} means medicine, but 薬{やく} is a slang word for drugs/narcotics.




According to [this dictionary entry](https://www.weblio.jp/content/%E8%96%AC)
薬{くすり} means medicine, but 薬{やく} is a slang word for drugs/narcotics.

