To detect contacthypersensitivity to cosmetics in patients with scalp pruritus by patch testing

Scalp pruritis is a common presenting complaint that is considered a diagnostically and therapeutically challenging situation. Contact dermatitis of the scalp can occur primarily after application of cosmetic products on healthy skin or secondarily on skin affected by dermatosis such as seborrhoeic dermatitis, psoriasis etc. Active ingredients of hair care products have been found to be the third most common cause of allergic contact dermatitis. Objective To identify the common topical medicaments and cosmetics capable of producing scalp pruritus and value of patch testing in these situations. Materials and methods 20 patients with history of scalp pruritis were patch tested with cosmetic series kit of chemotechnique diagnostics AB Sweden and in addition, patients own products were also tested. For wash off products like shampoos patch test was done at a concentration of 1:10. The reading was taken at 48hrs and 72hrs, and results interpreted according to the ICDRG criteria. Results Out of 20, 17 patients were positive for one or more allergens. Paraphenylenediamine (PPD) was found to be the most common allergen in 9 out of 20. Followed by gallate mix in 7 patients and cetrimonium bromide in 6 patients. And, 8 patients showed positivity for more than 2 allergens. Conclusion This study was undertaken to to identify allergens inducing pruritis of scalp by patch testing and to find the incidence of allergic contact dermatitis to topical preparetions and cosmetics among patients with pruritis of scalp. We recommend patch testing in patients with long standing pruritis of scalp