Tetrahydrofurfuryl Methacrylate and Isobornyl Acrylate

BACKGROUNDAllergic contact dermatitis from hearing aid ear moulds is infrequently reported.

OBJECTIVESTo identify cases of allergic contact dermatitis from hearing aid moulds in a cohort of patients investigated between 2022 and 2025 at Amsterdam University Medical Center.

MATERIALS AND METHODSRetrospective analysis of patients referred for investigation of suspected allergic reactions to ear moulds.

RESULTSOf 20 patients with suspected allergic reactions to ear moulds, 8 (40%) had positive patch tests to (meth)acrylates considered to be probably relevant. All eight reacted to tetrahydrofurfuryl methacrylate, of whom five had a positive reaction to this hapten only. The other three all co-reacted to isobornyl acrylate and 1,6-hexanediol diacrylate. None had positive patch tests to hydroxyethyl methacrylate.

CONCLUSIONSThere are strong indications that tetrahydrofurfuryl methacrylate and isobornyl acrylate are relevant contact allergens present in hearing aid ear moulds. Hydroxyethyl methacrylate did not identify a single case of contact allergy to these materials.

Abstract from PubMed