So it’s not the actual henna – it’s an additive to make the henna darker in hue. Para-phenylenediamine (PPD) is an aromatic diamine related to aniline added to henna to accelerate the dyeing process. The toxicity of PPD includes skin irritation, contact dermatitis (painful rash), severe injury to the eye if placed in or near the eye including swelling of the eyeball itself (chemosis), tearing (lacrimation), or even permanent blindness. Ingestion of PPD produces two types of toxic effects. The first consists of rapid development of severe edema (swelling) of the face, neck, pharynx, tongue, and larynx with respiratory distress, often requiring tracheostomy. In the later phase, rhabdomyolysis (muscle breakdown) and acute tubular necrosis (kidney failure). Vomiting, gastritis, hypertension, vertigo, tremors, and convulsions have been reported.