September 2011 in “Daehan miyong hakoeji” Henna orange powder, especially with alkali, protects and colors hair better than oxidizing colorants.
March 2007 in “The FASEB Journal” Henna mixed with PPD can cause skin reactions, scarring, and a specific type of baldness, and needs more research to understand these effects.
September 2023 in “Clinical, cosmetic and investigational dermatology” SLFC can improve scalp health and reduce sensitive scalp symptoms.
September 2023 in “International Journal of Cosmetic Science” Both shampoos increased scalp germ numbers but did not change the overall microbial community composition.
April 2024 in “Pharmacognosy research” The herbal hair dye with natural ingredients like henna was successfully made and tested, but more research is needed on its effectiveness on different hair colors and benefits.