Petrolatum is often useful for reducing moisture loss, but it should not be presented as completely Malassezia-inert. One laboratory study found growth of M. furfur with white petrolatum, while broader cosmetic-ingredient testing found little or no growth for most tested species with paraffin-based materials. This mixed result is a theoretical caution, not proof that petrolatum causes seb derm flares.

For ordinary skincare, the barrier benefit may still outweigh that uncertain signal, especially on a small, dry area in a simple formula. Petrolatum does not treat the underlying seb derm process, and its heavy feel may not suit oily or warm areas. Use the simplest product that stays comfortable and stop if petrolatum repeatedly increases itching, redness or congestion.