This paper records three cases of contact dermatitis caused by dichlorophene (G-4) and includes clinical photographs of two of them. Appropriate patch tests proved the offending agent and determined the degree of hypersensitivity in each patient. A chlorinated phenol, dichlorophene is an effective preservative used in a commercially available modification of Unna's boot (Gelocast), in many cosmetic products, and in some dermatologic therapeutic agents. It is also employed to prevent fungal and bacterial deterioration of cotton and woolen textiles, paper products, rug backing, cutting oils, and canvas lawn and beach furniture. Despite the structural similarity of dichlorophene to hexachlorophene, our patients did not show cross-sensitivity. Dichlorophene's sensitizing potential is discussed and compared with that of parabens, sorbic acid, quaternary ammonium compounds, organic mercurials, and other preservatives.
Schorr WF. Dichlorophene (G-4) Allergy. Arch Dermatol. 1970;102(5):515-520. doi:10.1001/archderm.1970.04000110031005