Henna

Henna contains hennotannic acid, a dye that bonds with the collagen in skin cells and keratin of fingernails and hair, leaving behind a reddish-brown stain. Henna is the oldest documented cosmetic and is soothing and cooling on the skin. It alleviates heat exhaustion and is even a natural sun block. Henna is a reddish dye prepared from the dried and powdered leaves of the henna tree. It has been used since at least the ancient Egyptian period as a hair and body dye, notably in the temporary body art of mehndi (or "henna tattoo") resulting from the staining of the skin using dyes from the henna plant.