AUTHORS: David Basketter, DABMEB Consultancy Ltd, Kingswood, UK; Nicholas Plunkett, Trichocare Diagnostics, London, UK; Klaus E Andersen, Odense, Denmark; Curt Hamann, SmartPractice, Phoenix, USA

BACKGROUND: Permanent hair colourants face consumers with the risk of allergic reactions, largely due to dermal exposure to p-phenylenediamine (PPD) and its cross-reacting derivatives. To mitigate this risk, hair colourant manufacturers recommend consumers undertake a self-test 48 hours prior to colouring to indicate whether they may be allergic. This has been repeatedly criticised as non-standardised, lacking independently verified proof of safety and efficacy. Colourstart is licenced by the UK Medicines and Healthcare products Regulatory Agency (MHRA) to screen for allergy to hair colour (PPD).

OBJECTIVE: To update information from the first licensed consumer test system for hair colour allergy (PPD), Colourstart.

METHOD: Outcomes of the use of Colourstart patch test and its associated allergy questionnaire were collated over a period of 3 years.

RESULTS: Since launch in March 2021, approximately 58000 consumers have used Colourstart. Pharmacovigilance only identified 18 (0.03%) non-serious adverse events (e.g. redness or skin staining).  Approximately nine-tenths (51000/58000) applied enhanced instructions for use to record their results online to share with their Hair Professional. Of this group, 309 (0.7%) self-reported a positive test result, alerting them and their hair professional to avoid all oxidative hair colourants.

CONCLUSION: These results corroborate the previous evidence that Colourstart is a safe and effective system for delivering an allergy alert to potential users of permanent hair dye.