Allergic contact dermatitis to a henna tattoo

• Henna (Lawsonia unermis, family Lythraceae) is a shrub cultivated in India, Sri Lanka, and North Africa - Henna contains lawsone (2-hydroxyl-1,4-naphthoquinone) as the active substance
  • henna dye is obtained from the dried leaves of this plant - the dried leaves are powdered and mixed with oil or water, and used to prepare hair and body dyes
  • traditionally Henna tattoos are used during marriage ceremonies and other celebrations to draw floral or geometric motifs on the hands and feet of participants
  • in order to be used as a temporary paint-on tattoo, henna is applied to the skin with a brush and left for several hours
    • the color of henna dye varies between countries and ethnic groups:
      • the henna used in Africa is generally black
      • the henna used in India is reddish brown
      • to obtain different shades, various natural substances such as vinegar, lemon oil, eucalyptus oil, or instant coffee powder may be added
      • immediate and delayed hypersensitivity to pure henna have been described - although it is extremely rare (2)
      • para-phenylenediamine (PPD) is also sometimes added to obtain a dark, blackish henna
        • PPD is this substance that causes the majority of cases of contact dermatitis reported in subjects with tattoos
        • PPD is found in hair dyes, up to a maximum concentration of 6%, but is not licensed for application to the skin (2)
        • PPD is known to be allergenic and several reports have confirmed its presence in temporary tattoo reactions

A temporary tattoo may result in unpleasant side-effects and permanent sequealae (2):

• lichenoid reactions and erythema multiforme are generally self-limiting - although treatment with steroid creams may be required
• severe reactions to PPD have been reported including angioedema progressing to renal failure and death
• post-inflammatory hyper/hypo pigmentation and/or scarring may occur secondary to a temporary tattoo

A series of case reviews of allergic contact dermatitis from henna tattoos concluded that "the addition of coloring chemical agents such as p-phenylenediamine and p-toluidenediamine to the traditional mixture may lead to a risk of developing an allergic contact dermatitis when having a henna tattoo (1)."

Reference:

1. Neri I et al (2002). Childhood allergic contact dermatitis from henna tattoo. Pediatr Dermatol.;19(6):503-5.
2. Prescriber (2004); 15 (10): 62.