Armpit rashes can be caused by allergic reactions, infections, and chronic conditions. Armpits are a common place to get rashes because the skin there is thin, folds up on itself, and can be hairy.

An allergic reaction to fragrance occurs when ... red lumps that form in areas where skin rubs together, like the armpits or ...

The elbow, armpits, knees, breasts ... Different sorts of smells may cause allergies in some people. Such allergies might result in pain and headaches. Trying a little beforehand is beneficial.