If you have been using a commercial deodorant or antiperspirant, check the label to see if it contains any type of aluminum, alum, petroleum or propylene glycol, which can lead to the buildup of chemicals under your arms. This can result in irritation, hygiene problems, or worse. Antiperspirants may leave a residual of alum salts in the underarm. Even over a short period of time undetermined DNA damage can occur under your arms.