There is not enough ingredient-specific evidence to label Hydrochloric Acid itself good or bad for seborrheic dermatitis. In cosmetics it is used in tiny controlled amounts to adjust pH, not as a treatment or an exfoliating active.

The danger of concentrated raw acid does not describe a correctly formulated product, where it is diluted and often neutralised as the final pH is set. No applicable Malassezia evidence was found. Check whether the finished product feels comfortable and appropriately gentle rather than judging it by the raw ingredient name.