The stain is mostly likely caused by bacterial growth not the antiperspirant itself. Antiperspirant is an aluminum chloride salt which is an inorganic compound. There is some information available that antiperspirants can promote bacterial growth which will result in common yellow underarm stains. Even if the antiperspirant isn't promoting the bacterial growth, it also doesn't appear to be stopping the perspiration which ultimately is causing the stain.

Some deodorants have a bacteria inhibitor to curb the bacterial growth. Try switching to a deodorant rather than an antiperspirant. Be sure the deodorant inhibits bacterial growth and is not just a fragrant mask.

- Updated: February 21, 2006