About 1 in 5 people in the general population has a contact allergy to at least one common ingredient or material. Women are more than twice as likely to have contact allergies as men (28% vs. 13%). Nickel is by far the most common culprit at 11%, followed by fragrance mix, cobalt, and preservatives.

Researchers analyzed 28 studies covering over 20,000 people who underwent patch testing (the standard way to identify contact allergies). They pooled the data to calculate overall prevalence rates across different groups.

Funding not disclosed in abstract