Allergic Eczematous Reactions of the Nail Bed Due to "Under Coats"

Cosmetic dermatitis – current perspectives

“…Nail varnish contains phenol formaldehyde resin, which is responsible for contact sensitivity of the base coat 55 . This may also cause subungual hemorrhage, red–brown discoloration of the nail plate, onycholysis, and hyperkeratosis under the nail 56 …”