Introduction - henna
Introduction - black henna tattoo
Introduction - black henna tattoo reaction
Demographics
Clinical features
Diagnosis
Treatment
Avoidance
Henna is a flowering plant that has been used since medieval times to stain skin, hair, and fingernails a light brown colour due to its active ingredient naphtha-quinone.
Henna is used to celebrate various occasions such as weddings in Hindu and Middle Eastern cultures in India, Pakistan, Sudan, Libya and many other countries.
Temporary paint-on tattoos do not involve needles and usually fade after 3 weeks.
To make them temporary henna tattoos look more like a real tattoo, para-phenylenediamine (PPD) is added to make ‘black henna’.
The procedure is also called pseudo-tattooing.
Black henna tattoo reaction is a form of allergic contact dermatitis to PPD.
Natural pure henna does not cause allergic reactions. Nor do other possible additives such as vinegar, olive oil, coal and cloves.
Henna tattoo reactions have mostly been reported to affect tourists visiting the Middle East or South East Asia, especially Bali, Morocco, Turkey and Egypt. Reports are also now appearing from tattoos applied in Europe and the USA. Temporary paint-on ‘tattoos’ have usually been applied by transient street artists.
Both children and adults can be affected.
Slow acetylators are more prone to developing the allergy than fast acetylators.
The concentration of PPD in black henna has been found to exceed the regulated levels in most countries. Often kerosene or petrol is also added to improve the uptake of the colour. This seems to increase the risk of sensitisation and may cause irritant reactions.
PPD is also present in hair dyes and dark clothing dyes and is used in the rubber industry. Sensitisation can develop with exposure to any of these and once it has occurred reactions may then appear with other sources including chemicals with a similar structure such as azo dyes, parabens, para-aminobenzoic acid and para compounds. Cases have been reported where the initial sensitisation occurred with a hair dye and a rapid and severe reaction then developed to the paint-on tattoo. Others have been sensitised by the tattoo and have later reacted to hair dyes, clothing dyes and a marker pen. Intoxication with PPD has been reported to rarely result in systemic adverse effects including acute renal failure, rhabdomyolysis and multiple organ failure.
The contact allergic reaction usually appears in the pattern of the tattoo 7–14 days after first exposure. In someone already sensitised to PPD due to earlier exposure to the chemical, the reaction develops within 48 hours.
The reaction slowly resolves but can leave either increased pigmentation or a white outline of the original tattoo. Keloid scarring has been reported.
The diagnosis of black henna tattoo reaction is usually made on the history and clinical appearance.
Treatment generally involves the use of topical corticosteroids.
Minimise the risk of subsequent exposure to other sources of PPD (particularly permanent hair dye) and chemically related compounds once sensitisation has occurred.
We recommend avoiding exposure to temporary paint-on black henna tattoos, because of the high risk of sensitisation.
