Medicinal grade yellow and white petrolatum (soft paraffin) were tested for dermatoxic effects on laboratory animals and man. Yellow petrolatum produced redness, thickening of skin, hyperkeratosis and reversible total hair loss in rabbit and rat but no dermatoxic effect was observed in man and dog. White petrolatum which is similar in composition to yellow petrolatum produced less redness and keratosis. Refluxing of yellow soft paraffin with 95% alcohol could dissolve out dermatoxic fraction. The results have been discussed and it is suggested that drugs with petrolatum as ointment base should not be tested on rats and rabbits as petrolatum itself is dermatoxic in these species.

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