Softisan--a new vehicle for patch testing.

Petrolatum is a good vehicle for many patch test allergens, because it is stable, unreactive, and allergy to it is rare. Some difficulties exist, however, when water-soluble allergens are tested, because emulsifiers are often needed; these can change the properties of both the test material and the vehicle itself. In the present study, we compared petrolatum with a new lanolin substitute based on vegetable fatty acids as a patch test vehicle for nickel sulphate.