What's it called when you think you feel better but you are still sick

Question

I swear there is a word for thinking something when its really just your mind pretending it.

i.e You are sick and have an Advil and immediately feel better. (Even though it might not have kicked in yet.)

Answer 1

I think you are looking for the expression placebo effect:

• improvement in the condition of a patient that occurs in response to treatment but cannot be considered due to the specific treatment used.

(M-W)