If you don't change deodorant brands often your arm pits may rebel. It happened to me, so I researched the internet looking for an answer to the allergy, and came up with alum as a deodorant answer. It's a hypoallergenic deodorant and a great after shave, as many at the Shave Den know.
I use it myself. It works well and (of course) has no scent. I really do not want an artificial scent in my deodorant.
Guess I'm one of the lucky ones. I've been using Brut ant-perspirant/deodorant exclusively for 30-some-odd years. The stuff works great. I've worked some pretty hot days and soaked a few shirts in my time, but the pits are always dry.
I am not into Brut products, but their deodorant containers work great for travel shave stick holders and travel brush holders. They couldn't work better.