title: Methylisothiazolinone, an emerging allergen in cosmetics?
abstract: BACKGROUND
  A few cases on primary sensitization by, and occupational contact dermatitis from, methylisothiazolinone in paints and glues have been published. In cosmetics, methylisothiazoline (MI) is permitted in a concentration of 100 p.p.m., while 15 p.p.m. for the mixture of methylchloroisothiazolinone and methylisothiazoline (MCI/MI).
  
  
  OBJECTIVE
  To present cases of sensitization to, and allergic contact dermatitis from, cosmetic products containing methylisothiazolinone only.
  
  
  METHODS
  Seven patients with suspected contact dermatitis - six of them with (peri-)anal lesions and one with facial dermatitis - were patch tested with the baseline series, the own products exposed to, cosmetic ingredients, as well as with methylisothiazolinone 1000 p.p.m. and MCI/MI 200 p.p.m.
  
  
  RESULTS
  The patients with anal lesions had become sensitized by wipes for intimate hygiene, and one patient with facial dermatitis by a make-up remover, all containing methylisothiazolinone only. Three out of seven cases would have been missed if only MCI/MI 100 p.p.m., as present in the baseline series, had been tested.
  
  
  CONCLUSIONS
  The inclusion of methylisothiazolinone as a preservative in cosmetics might not represent the solution to the problem of allergic contact dermatitis from isothiazolinones, since it leads to primary sensitization.
authors.affiliation: Faculty of Medicine, Department of Dermatology, University of Santiago de Compostela, University Hospital Complex, Spain.
authors.forename: Juan
authors.initials: J
authors.lastname: García-Gavín
authors.forename: Sara
authors.initials: S
authors.lastname: Vansina
authors.forename: Stefan
authors.initials: S
authors.lastname: Kerre
authors.forename: Alix
authors.initials: A
authors.lastname: Naert
authors.forename: An
authors.initials: A
authors.lastname: Goossens
mesh_terms: D000328:Adult; D000485:Allergens / Q000009:adverse effects*; D003358:Cosmetics / Q000009:adverse effects*; D017449:Dermatitis, Allergic Contact / Q000175:diagnosis / Q000209:etiology*; D009783:Dermatitis, Occupational / Q000175:diagnosis / Q000209:etiology*; D005148:Facial Dermatoses / Q000139:chemically induced / Q000175:diagnosis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010328:Patch Tests / Q000379:methods; D011310:Preservatives, Pharmaceutical / Q000009:adverse effects*; D013844:Thiazoles / Q000009:adverse effects*; D055815:Young Adult
chemical_list: D000485:Allergens; D003358:Cosmetics; D011310:Preservatives, Pharmaceutical; D013844:Thiazoles; C011506:2-methyl-4-isothiazolin-3-one; C011421:5-chloro-2-methyl-4-isothiazolin-3-one