Sodium Benzoate is generally a lower-concern ingredient for seborrheic dermatitis when used within the conditions of a properly formulated cosmetic. Its job is to help keep the product from spoiling, not to kill Malassezia or treat inflammation on your skin.

Preservative use inside a bottle cannot be translated into a seb derm treatment claim. Personal sensitivity or irritation from the complete formula is still possible, especially on broken skin. The ingredient's presence alone is usually less informative than whether the product stays comfortable in use.