^the boxes say "do not use on hands"
What's the worst that could happen? I've done it before and noticed no issues.
The skin on the hands can have allergic reactions that are caused by different things than skin allergies elsewhere on the body. So, it is relatively rare, but possible, that an antiperspirant that one can use quite safely elsewhere could cause an allergic reaction causing one of the various forms of dermatitis. Symptoms range from mild to quite nasty and can last for quite some time (weeks).
Interesting. It would be easy to put a dab on and check though (as they recommend with virtually all skin products anyway). The percentages must be very low.
Baby powder?