The first question most people ask about antiperspirant is not which one works the best, it's whether or not the health scares associated with it are legitimate. Does the aluminum in it cause Alzheimer's? Is it true that because you don't sweat them out, evil toxins trapped in your body by antiperspirant will fester and give you breast cancer? Both of these claims are false, regardless of alarmist mass e-mails to the contrary. But there are less dramatic health concerns related to deodorant and antiperspirant. A search of the Medline database turns up loads of articles on contact dermatitis caused by antiperspirants—they are the cosmetic product most commonly associated with skin irritation.