An Emerging Epidemic of Allergic Contact Dermatitis Due to Phytonadione Epoxide (oxidised Vitamin K1).

BACKGROUND:Reports of allergic contact dermatitis (ACD) to phytonadione epoxide (PE) in cosmetics suggest that PE is as powerful a sensitiser as its parent compound phytonadione. OBJECTIVE:To evaluate a case series of ACD to PE in Spain. METHODS:We reviewed the records of 20 patients with ACD to cosmetics containing PE diagnosed across Spain between January 2019 and June 2023. RESULTS:All 20 patients developed patch test (PT) or repeated open application test (ROAT) reactions to cosmetics containing PE. All involved women with eyelid eczema. PT or ROAT with PE preparations were positive in 17/20 (85%). PE at 1%, 5%, 10% and 20% in pet. was patch-tested in 8/17, 14/17, 11/17 and 8/17 patients; being positive in 6/8 (75%), 13/14 (92.85%), 11/11 (100%) and 8/8 (100%), respectively. CONCLUSION:Regulators should, not only ban the specific dangerous cosmetic ingredients, but also consider to ban or keep under close surveillance those closely related products or derivatives that might potentially cause similar harmful effects. PTs with PE are suggested to be performed at a 5% concentration in pet. Higher concentrations (10% pet.) should be tested whenever PTs with 5% pet. PE are negative.