title: Relationship between formaldehyde and quaternium-15 contact allergy. Influence of strength of patch test reactions.
abstract: BACKGROUND
  In groups of patients with formaldehyde allergy, many have positive patch tests to quaternium-15. Conversely, of patients allergic to quaternium-15, over half also react to formaldehyde.
  
  
  OBJECTIVE
  To test our hypothesis that patients with stronger patch test reactions to formaldehyde are more likely to react to quaternium-15, attesting to the aetiological role for formaldehyde in such co-reactivity.
  
  
  METHODS
  Retrospective analysis of all patients patch tested with formaldehyde and quaternium-15 in the European baseline series between 1994 and 2009 (TRUE test).
  
  
  RESULTS
  In a group of 86 patients allergic to formaldehyde, 73% co-reacted to quaternium-15; in the subgroup of 70 women, the percentage was 83. In both groups, more reactions were observed to quaternium-15 in the patients with a ++ reaction compared to the patients with a + reaction to formaldehyde. Conversely, stronger reactions to quaternium-15 were significantly more often associated with formaldehyde sensitivity in a group of 107 patients reacting to quaternium-15 and a subgroup of 88 women. In men, such effects were not observed and only 5 of 16 (31%) men allergic to formaldehyde also reacted to quaternium-15.
  
  
  CONCLUSIONS
  In women, but not in men, stronger reactions to formaldehyde lead to more positive quaternium-15 patch tests.
authors.affiliation: Department of Dermatology, University Medical Centre Groningen, University of Groningen, PO Box 30.001, 9700 RB Groningen, The Netherlands.
authors.forename: Anton C
authors.initials: AC
authors.lastname: de Groot
authors.forename: Janine
authors.initials: J
authors.lastname: Blok
authors.forename: Pieter-Jan
authors.initials: PJ
authors.lastname: Coenraads
mesh_terms: D003429:Cross Reactions; D017449:Dermatitis, Allergic Contact / Q000209:etiology*; D005260:Female; D005557:Formaldehyde / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008709:Methenamine / Q000009:adverse effects / Q000031:analogs & derivatives*; D010328:Patch Tests; D011310:Preservatives, Pharmaceutical / Q000009:adverse effects*; D012189:Retrospective Studies
chemical_list: D011310:Preservatives, Pharmaceutical; D005557:Formaldehyde; C018375:quaternium-15; D008709:Methenamine