Toluene‐2,5‐diamine may be an isolated allergy in individuals sensitized by permanent hair dye

Contact allergy to common ingredients in hair dyes

“…PTD is found more often than PPD in permanent hair dyes in Sweden (24) and Denmark (21), but the reverse is true in Spain (25). PPD and PTD have very similar chemical structures, so cross-reactivity is expected, and concomitant reactions to PPD in those sensitized to PTD were found in 80.7% of cases (Table 3), similarly to what has been seen in previous investigations (23,26). Also, a high degree of concordance with PPD allergy was seen in those with positive patch test reactions to p-aminophenol (86.8%) or m-aminophenol (82.7%).…”

“…Other hair dye ingredients, such as PTD, p ‐aminophenol, m ‐aminophenol, and resorcinol, are also well‐known hair dye allergens , but have been much less studied.…”

“…Other hair dye ingredients, such as PTD, p-aminophenol, m-aminophenol, and resorcinol, are also well-known hair dye allergens (12,15,(18)(19)(20)(21)(22)(23), but have been much less studied. In our study, PTD came second after PPD with 2.8%, followed by p-aminophenol, m-aminophenol, and resorcinol ( Table 2).…”

p‐Phenylenediamine and other hair dye sensitizers in Spain

“…Thus, hair dye allergy may be underdiagnosed in dermatitis patients tested with the baseline series. In two retrospective analyses of patients patch tested with PPD and TDA simultaneously, 14% and 17% of those reacting to TDA tested negative for PPD (14,15). Consequently, the hair dye allergy in these patients would have been missed by the baseline series.…”

Contact dermatitis to 4‐amino‐2‐hydroxytoluene in hair dye

“…It is interesting that our patient reacted to three chemicals from a similar ‘cluster’, based on physiochemical properties and reactivity, used in the Søsted et al paper (5). This adds weight to their assertion that there is a plausible similarity in sensitization capacity within these groupings [this is in no way assured, however, as shown by Winhoven et al (7), who described isolated p ‐toluenediamine contact allergy in patients who showed no reaction to the chemically similar PPD].…”