Dermatitis is a reaction of the skin to a substance to which the body is allergic. Not all people will respond the same to the substances, some people develop a hypersensitivity to chemicals or organic substances called allergens. When exposed to these allergens, they develop an allergic reaction.
It commonly happens when a person buys a new pair of shoes where the concentration of dyes and chemicals in the shoes is high. It can manifest as dry, itchy, irritated skin.
In circumstances where a person’s foot perspires a lot, the chemicals ot dyes in the shoes may be more prevalent.
Treatment involves removing the source of the allergen, and changing to hypoallergenic footwear, and using cortizone cream to settle the condition. See your Podiatrist for a differential diagnoses, it can often be confused with athletes foot.