Apply Directly to the Forehead: Holmes, Nana, and Hennapecia

In the 2007 editorial from The FASEB Journal, the author highlighted the dangers of using henna mixed with para-phenylenediamine (PPD) for tattoos and hair dye, noting that the active component, lawsone, can lead to acute contact dermatitis, scarring, and keloid formation. The editorial reported an epidemic rise in adverse reactions since 1995 and identified henna as an occupational hazard for hairdressers, capable of inducing hemolytic anemia. A specific pattern of baldness, termed "hennapecia," was observed, particularly in older French women, which may be related to oxidative stress from the dye and its additives. The author urged for research to pinpoint the cause of "hennapecia." Despite FDA warnings about PPD-containing henna, regulation in professional salons remains outside its authority. The piece also contemplated the difference between observation and experimentation, referencing Emile Zola's literary methods.