未老先衰

wèi lǎo xiān shuāi

to age prematurely

wèi

not yet

lǎo

prefix used before the surname of a person or a numeral indicating the order of birth of the children in a family or to indicate affection or familiarity

xiān

beforehand; first; earlier

shuāi

(bound form) to decay; to decline; to wane