Is crystal deodorant safe?

[mcb2102]

My husband came home from the store with one of those "crystal" deodorants. It says it contains "ammonium alum" - that sounds like an aluminum compound. How can that be safe?

[t2009]

OP, I had the same question when I was using the crystal deodorant but I looked into it & it is not aluminum, it is a form of the ammonium. At least that's what my research at the time told me. It was many years ago, though, so I can't tell you 100%.