Getting a henna tattoo is an engaging experience for adults and children in the summer. After all, it is just for a few days. But you may end up regretting it. Tattoos made with black henna, whose decorative motifs may even include glitter, can trigger severe allergic skin reactions and permanent sensitization.
Henna is traditionally used in North Africa and other parts of Asia as a hair dye and in religious and ritual tattoos. This natural henna is dark green to brown in colour and lasts three or four days at most. But black henna can draw on the skin in a way more like the ink used in permanent tattoos because, as the name suggests, it is darker in colour. Its success on beaches, especially among children, is explained by the fact that it lasts longer and is easier to apply. To achieve this effect, various colours are added to the natural henna – which is where the problem lies, as they include paraphenylenediamine (PPD).
In black henna, PPD – in concentrations as high as 15% – can cause anything from a mild, scratchy eczema, swelling or a burning sensation to bumps or blisters.
In the most extreme cases, a person tattooed with a black henna drawing may become sensitized to this substance for life and experience allergic reactions from interactions with antimicrobial drugs (sulfonamides), antihistamines, certain local anaesthetics (like the benzocaine used by dentists) and even para-aminobenzoic acid (PABA), an ingredient in sunscreens.
It is not a question of scaremongering: henna tattoos should be viewed with caution. Allergic reactions can be life-threatening, so make sure that the henna is genuinely natural. Or simply opt for some other form of personal decoration this summer.
Anna Solana, science journalist