Causes

• One of the products often added to black henna to give it a dark color is the chemical paraphenylenediamine, known as PPD. According to the FDA, while PPD has only been approved for use in hair dyes, they have received several reports of PPD causing an adverse reaction when applied directly to the skin. Because the Fair Packaging and Labeling Act does not apply to products used exclusively by professionals such as henna artists, consumers often are not aware of what is being applied to their skin when receiving a black henna tattoo.
  
  

Symptoms

• The most common reaction to PPD is contact dermatitis in the form of skin inflammation, blisters and open sores. Symptoms usually appear within three to 10 days of contact and can last for weeks, though if you are already sensitive to PPD they can appear much more quickly. In rare cases PPD can trigger anaphylaxis, a life-threatening, multisystem allergic reaction that can constrict the airway and affect heart rhythm.
  
  

Treatment

• Doctors treat contact dermatitis with corticosteroids, such as triamcinolone, in the form of an ointment or cream that is rubbed onto the affected area. More serious reactions such as anaphylaxis require emergency medical intervention.
  
  

Long-term Effects

• Skin affected by an allergic reaction to PPD in black henna can create scar tissue and the pigment of the skin in the area of the tattoo can permanently change. Once a person has had an adverse reaction to PPD, he can experience long-term sensitivity and develop reactions to products he previously had no problem with including hair dye, darkly dyed clothing, sunscreen and some medications.
  
  

Prevention

• Avoid products advertised as black henna, and ask henna artists for the ingredients of any darkly pigmented henna. Black henna containing PPD dyes the skin hours faster than natural henna, and the resulting tattoo can last for days or weeks longer. Be wary of any henna product advertised as having these traits.