Editorials

Allergy to hair dye

BMJ 2007; 334 doi: http://dx.doi.org/10.1136/bmj.39042.643206.BE (Published 01 February 2007) Cite this as: BMJ 2007;334:220
  1. John P McFadden, senior lecturer (john.mcfadden{at}kcl.ac.uk)1,
  2. Ian R White, consultant dermatologist1,
  3. Peter J Frosch, director2,
  4. Heidi Sosted, senior researcher3,
  5. Jenne D Johansen, director3,
  6. Torkil Menne, professor3
  1. 1St John's Institute of Dermatology, St Thomas' Hospital, London SE1 7EH
  2. 2Department of Dermatology, Hautklinik Stadtische Kliniken, University of Witten/Herdecke, D-44137 Dortmund, Germany
  3. 3National Allergy Research Centre, Department of Dermatology, Gentofte Hospital, DK-2900 Hellerup, Denmark

    Its incidence is rising, as more and younger people dye their hair

    For more than 100 years para-phenylenediamine (PPD) and other related members of the aromatic amine family have been the main agents used in permanent hair dyes, and more than two thirds of hair dyes currently contain PPD. This compound is an effective hair dye owing to its low molecular weight, its ability to penetrate the hair shaft and follicle, its strong protein binding capacity, and its rapid polymerisation in the presence of a coupler (a kind of catalyst) and an oxidising agent. However these properties also make PPD an ideal contact allergen and, indeed, it is among the most potent.1

    During the 20th century allergic reactions to PPD became such a serious problem that it was banned from hair dyes in Germany, France, and Sweden.2 Current European Union legislation allows PPD to comprise up to 6% of the constituents of hair dyes on the consumer market (3% when added to the oxidising solution required to develop the colour). No satisfactory or widely accepted alternatives to the aromatic amine agents are available for use in permanent hair dye.

    A patient with contact allergy to a hair dye often presents with dermatitis on the face or around the hair line. Severe reactions also occur; some patients have had such gross facial swelling that they have been treated initially for angio-oedema and some have been admitted to hospital.3 Contact allergy to PPD and related aromatic amine dyes is detected by patch testing using 1% PPD in petroleum jelly. This is included in most standard series of patch tests used to screen for contact allergy in patients with eczema. Such screening may, however, fail to detect allergic reactions to other hair dyes.4

    Dermatologists report anecdotally that the frequency of positive reactions to PPD on patch testing is increasing. This was confirmed in a recent retrospective survey in London, with a doubling in frequency over six years to 7.1% in a clinic for adults with contact dermatitis.5 This rise could not be attributed to an increase in occupational exposure (in hairdressers), medicolegal claims, the use of temporary “henna” tattoos containing high concentrations of PPD (often when on holiday),6 or a greater proportion of South Asian patients—who tend to have high rates of allergy to hair dye.7

    In the same London clinic from 1965 to 1975 between five and 11 patients with non-occupational PPD allergy were seen each year.8 More recently this figure has consistently exceeded 40 such patients annually. This increase is unlikely to be due to more consistent referral and diagnosis because only 15% of people with a history consistent with hair dye allergy seek medical attention, and of these only a minority are tested for allergy to hair dye.3 9

    Data from patch testing in Belgian and Portuguese centres confirm the pattern seen in London (personal communication by A Goosens to the European and Environmental Contact Dermatitis Research Group in Leuven, 2005), as do studies from Denmark,9 Germany,10 and Singapore.11 12

    In Bangkok screening of 2500 normal adult volunteers by patch testing showed a 2.7% prevalence of PPD allergy which, when extrapolated to the general population, suggests that more than one million Thai adults may be sensitive to PPD,w1 while in Germany up to 1.3 million adults in the general population may be sensitive.w2

    Market research indicates that more people are dyeing their hair and are doing so at a younger age. In 1992 a survey by the Japan Soap and Detergent Association of young people in Tokyo, 13% of female high school students, 6% of women in their 20s, and 2% of men in their 20s reported using hair colouring products.w3 By 2001 the proportions using hair colouring agents had increased in these three groups to 41%, 85%, and 33%, respectively. Furthermore, female high school students and young women were dyeing their hair at shorter intervals. In America the proportion of young men dyeing their hair increased by 25% in the five years after 1998.w4 One leading Japanese company saw its hair dye sales more than double in the 10 years up to 2001, and according to data from the Japanese government total shipments of hair dye to Japan doubled in the 10 years up to 2001.w5 In Denmark 75% of women and 18% of men have used hair dye,9 and the median age for first use of hair dye for both men and women is during the teenage years.9 Severe hair dye reactions among children have recently been reported.w6

    Wider debate on the safety and composition of hair dyes is overdue—among medical and scientific communities, the public, and legislators. Cultural and commercial pressures to dye hair and, perhaps, the widespread obsession with the “culture of youth” are putting people at risk and increasing the burden on health services. It may not be easy to reverse these trends, however, as some patients have continued to use such dyes even when advised that they are allergic to them and risk severe reactions.w7

    Footnotes

    • Extra references w1-w7 are on bmj.com

    • Competing interests: None declared.

    References