Allergic contact dermatitis is an itchy skin condition caused by an allergic reaction to material in contact with the skin. It arises some hours after contact with the responsible material, and settles down over some days providing the skin is no longer in contact with it.
The dermatitis is generally confined to the site of contact with the allergen, although severe cases may extend outside the contact area or it may become generalised. Sometimes the allergen is transmitted from the fingers so unexpected sites can be affected eg the eyelids and genitals. Dermatitis is unlikely to be due to a specific allergen if the area of skin most in contact with that allergen is unaffected. The affected skin may be red, swollen and blistered or dry and bumpy.