A recent study found the use of deodorant and antiperspirant affects the composition of underarm microbe colonies.

Many feel the development of antiperspirant and deodorant is among humankind’s greatest achievements, but it appears the products do more than keep odor at bay.
A recent study published in PeerJ found the personal hygiene boosters affect the composition of underarm microbe colonies. 
Testing involved a small group of 17 participants, some who regularly apply the products and others who do not.
Users were asked to forgo the products beginning on the second day, while those who typically abstain were instructed to slather them on towards the study period’s end.