I have migraines that are triggered by not only chemicals but also by scents. Trying to find a deodorant that doesn't cause problems one way or another can be difficult. I've found several that I could tolerate but they just couldn't hold up with me being active. Nature's Gate Organics Lemongrass and Clary Sage deodorant is the one I've finally settled on that doesn't aggravate my migraines either through scent or chemicals. It also holds up to me being outside working with my horses, even in the summer heat. It's hypo-allergenic, doesn't contain aluminum, nor does it leave a residue on my clothes, or under my arms.
I find the lemongrass and clary sage scent very pleasant. They do have other scents available, including one in lavender and one containing tea tree oil.
One of the qualities I also like about the Nature's Gate Organics is that their products are not tested on animals.