Cocamidopropyl betaine (CAPB) is a surfactant, and reports of allergic contact dermatitis to this chemical have been reported in the literature. Although most commonly found in rinse-off products, the chemical nonetheless has been shown to induce allergy. The actual component responsible for allergic reaction may be the final compound itself, CAPB, or one of the substances used in its synthesis that may be present as an impurity. Allergy to CAPB is most commonly seen in a head and neck distribution, although other patterns have been identified.