It is because adults who have learned about medicines know whats right for you
Curtail and work harder so your effort is noticed more
Yes, it can cause many physical health issues
Unexpected means it was something you did not "expect" to happen such as a car crashing into you which means this is wrong.
Unfair is any injury.
Unnecessary means it was never needed and could have been prevented/not done therefore unnecessary is the best term.
