Is Henna Safe?

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

“[T]he average adult uses nine personal care products each day, with 126 unique chemical ingredients.” Now, we used to think that anything applied to the skin would always just “remain on the surface,” and the only thing you had to worry about was like local skin irritation. But, over recent decades, we’ve started to recognize “that some topically applied substances can penetrate into or [even] through human skin” and end up circulating throughout our bodies.

Take the toxic heavy metal lead, for example. To see if lead could be absorbed through the skin into the body, researchers applied lead to someone’s left arm, and then they measured the level of lead in the sweat coming off their right arm over the next few days. And there was a big spike, proving, nearly 30 years ago, that “lead can be absorbed through [the] skin” and rapidly distributed throughout the body.

This has led public health authorities to “recommend that parents avoid using cosmetics [at least] on [their] children that could be contaminated.” Which cosmetics might those be? Lead has been found in a wide range of cosmetic products, because it’s a natural constituent of many color pigments. The FDA has set an upper limit for lead at 20 parts per million, and though only some samples of “henna” exceeded that, because henna is used for temporary tattoos, these quantities of lead can remain on the skin for a long time and may not be safe. This is because studies show that lead “may have no identifiable safe exposure level, with even the lowest levels shown to affect [the brains of developing] children.”

“Thus, the use of henna especially among children may constitute a public health risk.” So, “[i]ncreasing awareness of henna’s serious toxic implications [may help end, or at least reduce] the use of such hazardous material especially when children are involved.”

Now, traditionally, henna was just the dried powdered leaves of a plant. But, more recently, other ingredients have been added “to give it a stronger color”—added ingredients such as lead, “one of the most common and egregious additives in henna.” But, not as common as PPD (para-phenylene-diamine).

“The red paste traditionally used, known as ‘red henna,’ rarely produces adverse effects.” But, to “help achieve a darker pigment, known as ‘black henna’,” various additives may be used, including animal urine. But, better pee than PPD, a coal tar derivative that can cause nasty skin reactions such as blistering and scarring. PPD is added to speed up the process from as long as 12 hours down to less than two hours. So, while the “[u]se of black hennas may be tempting,” it has the potential for both short- and long-term side effects.

How common are these reactions? The best estimate is about 2.5%. So, one in 40 kids who get a black henna tattoo may have an allergic reaction. Unfortunately, this practice “has become fashionable” (thanks a lot, Spice Girls). There’s no such thing as “natural black henna.” So,
“[p]erhaps it is best to respect the traditional practice…lest a temporary tattoo [turn into] a permanent scar.”

The problem is that “PPD can be found in products labeled as ‘red henna,’ too.” So, just because it’s red doesn’t mean it’s not risky. Bad news for the $100 million industry.

Because henna of all colors is so often adulterated, under FDA guidelines, “henna should not be applied to the skin at all.”

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• Jallad KN, Espada-jallad C. Lead exposure from the use of Lawsonia inermis (henna) in temporary paint-on-tattooing and hair dying. Sci Total Environ. 2008;397(1-3):244-250.
• Basas CG. Henna tattooing: cultural tradition meets regulation. Food Drug Law J. 2007;62(4):779-803.
• Wang MX, Maranda EL, Cortizo J, Lim V, Jimenez J. Henna--A Temporary Body of Art. JAMA Dermatol. 2016;152(3):290.
• De Groot AC. Side-effects of henna and semi-permanent 'black henna' tattoos: a full review. Contact Derm. 2013;69(1):1-25.
• Florence TM, Lilley SG, Stauber JL. Skin absorption of lead. Lancet. 1988;2(8603):157-8.
• Bocca B, Pino A, Alimonti A, Forte G. Toxic metals contained in cosmetics: a status report. Regul Toxicol Pharmacol. 2014;68(3):447-67.
• Kmietowicz Z. "Black henna" tattoos can cause blistering and scarring, doctors warn. BMJ. 2015;351:h4519.

Image credits: tortugadatacorp via Pixabay and Michael Korcuska via flickr. Images have been modified.

Motion graphics by Avocado Video.

• children
• FDA
• heavy metals
• lead
• skin health