Concomitant topical medication, medicated or abrasive soaps and cleansers, soaps and cosmetics that have a strong drying effect and products with high concentrations of alcohol, astringents, spices or lime should be used with caution because of possible interaction with tretinoin. Particular caution should be exercised in using preparations containing sulfur, resorcinol or salicylic acid with Retacnyl cream. It is also advisable to "rest" a patient's skin until the effects of such preparations subside before use of Retacnyl cream is begun.