Henna has been used throughout Africa, India and the Middle East for thousands of years. It is a useful dye that has historically been used to dye hair and fabrics. Most people will associate henna with tattoos, however, which is only fair given that henna tattoos are very popular across the world and particularly so in Indian and Chinese culture.
Getting a temporary tattoo might seem like a fun way to remember an experience, however just because the tattoo is temporary does not mean that it isn’t going to be harmful.
Henna for body decorations is made by drying the leaves of a henna plant and crushing them into a fine powder. Water and a little oil is then added to make it into a paste. The paste is applied to the body and it stains the top layer of the skin. The average person will have their temporary tattoo for one to three weeks, or sometimes up to a month.
Because henna typically produces a brown, orange-brown, or reddish-brown tint, other ingredients must be added to produce other colors, such as those marketed as "black henna" and "blue henna." Even brown shades of products marketed as henna may contain other ingredients intended to make them darker or make the stain last longer on the skin. It is very important, therefore, to make sure ALL of the ingredients in the product being applied are safe.
The extra ingredient used to blacken henna is often a coal-tar hair dye containing p-phenylenediamine (PPD), an ingredient that can cause dangerous skin reactions in some people. That's the reason hair dyes have a caution statement and instructions to do a "patch test" on a small area of the skin before using them. Sometimes, the artist may use a PPD-containing hair dye alone. Either way, there's no telling who will be affected. By law, PPD is not permitted in cosmetics intended to be applied to the skin.