Picture of Allergic Contact Dermatitis (Arm)

Allergic Contact Dermatitis on Arm. This example of allergic contact dermatitis is a reaction to a henna tattoo on the arm, after ten days. Contact dermatitis is a type of eczema caused either by a toxic reaction to some substance or by an allergic reaction. The rash will generally clear up on its own if you can avoid contact with the what triggered it in the first place.