however , the style of the application may induce both allergic and photoallergic contact dermatitis from the nsaids and their ingredients . we describe a case of allergic contact dermatitis with diffuse erythematous reaction caused by allergic sensitivity to a component , diisopropanolamine , of a compress used by the patient . an 87-year - old japanese man with dementia presented with a pruritic eruption following the use of compresses for lumbago . the patient had used the same compresses for three weeks . during the last ten days of use , pruritic eruptions appeared on the bilateral lower back and upper buttock where the compresses were being applied . then , diffuse erythema developed on the trunk and extremities . physical examination revealed rectangular - shaped , pruritic exudative erythematous macular lesions on the bilateral lower back and upper buttock and diffuse erythema on the chest , abdomen , back and extremities ( fig . a patch test ( international contact dermatitis research group criteria ; finn chambers on scanpor tape , epitest ltd . , tuusula , finland ) was performed with the compress ingredients and the japanese baseline series . the positive reactions at both 2 and 4 days after application were to diisopropanolamine 1% pet . , fragrance mix 8% pet . ( brial allergen gmbh , greven , germany ) , and mercuric chloride 0.05% aq . it is used in emulsifying agents for cosmetic lotions , neutralizers in cosmetics , and bath preparations . until now , eight cases of allergic contact dermatitis from diisopropanolamine , including the present case , have been described ( table 1 ) . we previously reported a case of diffuse erythematic reaction after using compresses . in the previous case , three concomitant sensitizations to diisopropanolamine , felbinac , and crotamiton supposedly caused a diffuse erythematic reaction . in the present case , a single sensitization to diisopropanolamine was associated with a diffuse erythema . thus , similar phenomena of allergic contact dermatitis with diffuse erythematous reaction may be caused by allergic sensitivity to a different component or different combinations of ingredients in the topical medicament . patch testing with full ingredients from the manufacturer is essential for detecting the sensitized allergens in each case .