Although contact allergy to formaldehyde 1% decreased in this 10-year time period, contact allergies to formaldehyde and formaldehyde-releasers overall remain frequent in patients. In most cases, formaldehyde-allergic patients are exposed to ≥1 products containing formaldehyde. Improved regulation on permitted amounts of free formaldehyde in cosmetics is still warranted, including direct labelling of formaldehyde when it is present in small but relevant amounts.