Lawsone is a natural dye found in the leaves of the henna plant (Lawsonia inermis). It's a complex molecule that binds to the keratin in skin and hair, producing a reddish-brown stain.

It's important to note that while pure henna is generally safe for use on skin, some products may contain other chemicals, like paraphenylenediamine (PPD), which can cause allergic reactions and skin irritation.

Always check the ingredients list of any henna product to ensure it contains only pure henna.