Emollients in the prevention of frostbite.

47% of Finnish conscripts had had at least one frostbite of the head (42% on the ears, 23% on the face) at the age of 19. Non-medicated ointments are traditionally used in Finland for protection against facial frostbite without scientific evidence of their benefit. In studies on cold protecting emollients it was found that 21% of the male conscripts in Finland had used them in the cold. 84% of the users had experienced their effect as somewhat or clearly protective. However, in a controlled prospective epidemiological study of 913 cold injuries of the head, the use of cold protective ointments was associated with an increased risk of frostbite to the head (odds ratio 4.5 for ear frostbite, 5.6 for nasal frostbite and 3.3 for frostbite on other parts of the face). The thermal insulation provided by different emollients in the cold was minimal in in vitro experiments using a skin model. In in vivo studies with test subjects the skin on the applied half of the face cooled at least as quickly as the untreated half. However, when white petrolatum was applied, the subjective skin perception of a test persons was warming in the majority of the tests, in contrast to objective measurements. "Protecting" emollients seem to cause a false sensation of safety leading to an increased risk of frostbite probably mainly through neglect of efficient protective measures.