I learned that most antiperspirants contain aluminum which can cause dark underarms. Naturally Fresh Deodorant contains no harmful aluminum or skin irritants. I've been using this product for a week, and although I think it is too soon to see an improvement in my dark underarms, I'm really impressed with how it behaves as a deodorant! NF Deodorant is easy to use and leaves my skin feeling smooth and protected against perspiration odors. Just to be clear, this product is NOT an antiperspirant, and it will not keep you from sweating, but it will keep you from smelling like you are sweating. My real test took place while horseback riding (temps upper 80s!). I ride 2x a week and sometimes I can leave DRENCHED in sweat. I'm glad I purchased the NF Deodorant; I know it won't stain my clothes or further darken my underarms. I bought the unscented kind and I'm glad that I don't have to worry about the scent of my deodorant overpowering my perfume.