It's not an antiperspirant, just a deodorant. However, it apparently has ingredients in it that kill the bacteria that make your sweat stink.
Personally, I never found out. I used it a few days (not even long enough for my regular antiperspirant to get out of my system) and then it made me break out in a rash. Apparently I'm allergic to something they put in Toms.
I normally use the normal Dove white stick, but I'm pregnant and since I hit my second trimester, I've been really sweaty (I know, TMI!). I now use the Dove clinical stuff and put it on before bed (when I remember) - it works just great, even on my crazy pregnant sweat glands.