Why do my armpits burn when i put on deodorant?

Contact dermatitis: You either have an irritant or allergic contact dermatitis--a reaction to something your skin is coming in contact with. Most common agents are either fragrances or preservatives in topical products. Start with fragrance-free or unscented antiperspirants. You can add otc 1% cortisone cream to reduce irritation. If not better, see your local dermatologist.

Sensitive vs allergy: Sensitivity vs allergy to metal complexes, fragrances in deodorant.