expression, godan verb (-ru)
be beneficial; do good; be a lesson
Figurative expression meaning an experience (often a hardship or scolding) serves as good medicine for personal growth. Commonly used with the particle に to mark the beneficiary.
今回の失敗は彼にとって薬になるだろう。
This failure will probably be a good lesson for him.
厳
Harsh words can sometimes do you good.