IPA: /ɪmˈpɛərər/
KK: /ɪmˈpɛrər/
A person or thing that causes damage or weakness to something.
The medication can be an impairer of certain bodily functions if taken in excess.
Impairer → It is formed from "im-" (meaning not) and "pair" (from Latin "parare", meaning to make equal or prepare) with the suffix "-er" (meaning a person who). An impairer is someone who makes something not equal or diminishes its quality.
Think of someone who makes something 'not equal' or 'less' — 'im-' means not, and 'pair' relates to making equal.