Contact allergy to and allergic c…l review and update.

Formaldehyde releasers are preservatives still commonly used in cosmetics and personal care products that can trigger allergic contact dermatitis—even in people who aren't sensitive to formaldehyde itself. The EU has banned some of these ingredients (like quaternium-15), but others like bronopol and diazolidinyl urea remain legal and can cause localized rashes, airborne reactions, or widespread dermatitis. If you're allergic to one formaldehyde releaser, you may tolerate others, so patch testing individual ingredients matters.