Propylene Glycol is not automatically unsuitable for seborrheic dermatitis. It usually helps a formula hold water or carry other ingredients. In one small, older controlled study, a scalp solution containing 15% Propylene Glycol worked better than a similar alcohol-and-water solution without it. That is a useful clue, not proof that every skincare product containing it will help seb derm.

That study used a strong alcohol-based scalp solution, while a later study tested Propylene Glycol together with urea and lactic acid. Neither tells us how an ordinary moisturiser will feel on your skin. Some people in the combination studies reported smarting or burning, but the cause cannot be pinned on Propylene Glycol alone. Judge the complete product, and seek advice if it repeatedly stings or worsens your skin.