Contact dermatitis presents with redness and scaling. Scratching may thicken the skin and cause a lesion termed lichenification. This thickened form of eczema can itch intensely and is often habitually scratched and picked. Suspect infection if the redness intensifies or if there is any sign of pus and serum. Eczema can present in an acute form with redness and small blisters called vesicles. The rash then becomes red and scaly and eventually will disappear or become thick if scratched.

Allergic contact dermatitis to nickel in a belt buckle. Constant scratching has thickened the skin to produce a pattern of inflammation called lichenification.