Whether you go blonde, brunette, redhead—or even blue or pink—when you think about it, hair dye is a modern marvel. You apply it for a few minutes and then your new hair color can withstand shampoo, sweat, heat styling, and so much more, all while retaining its hue.
As it turns out, there’s one ingredient, in particular, that’s responsible for that longevity: PPD. To learn more about this ubiquitous color ingredient, we reached out to the experts: board-certified dermatologists Annie Chiu, MD, and Anar Mikailov, MD, FAAD, and trichologist Kerry E. Yates. Read on for what they had to say.
Meet the Expert
“Paraphenylenediamine (PPD) is the coloring ingredient in some hair dyes,” says Chiu. “It is a chemical that is used in permanent hair dye to give dyed dark hair a natural look. It also allows dyed hair to be permed and shampooed without losing its color.”
TYPE OF INGREDIENT: Chemical substance.
MAIN BENEFITS: Provides long-lasting hair color, helps protect against fading, and gives hair dye a natural appearance.
WHO SHOULD USE IT: Anyone looking to extend the life of their hair color.
HOW OFTEN CAN YOU USE IT: As often as hair is colored. “Hair dyes containing PPD—which is found in about 90 percent of hair dyes, including organic ones—are safe to use as often as you need to dye your hair as long as you take precautions and do not use if you have had an allergic reaction in the past,” Chiu says. “Hair dyes with PPD are strictly regulated in the U.S.”
What Is PPD?
“PPD is considered a primary intermediate for permanent hair color formulas,” shares Yates. “A primary intermediate is the main component of any oxidative hair dye formulation. It reacts with a dye coupler to form a larger dye molecule inside the hair cortex. This type of dye can be found in industry-leading brands like L'Oréal, Revlon, and Clairol.”
PPD hair dyes usually come packaged in two bottles, one containing the PPD dye preparation and the other containing the developer or oxidizer, Chiu explains. “PPD is a colorless substance that requires oxygen for it to become colored,” she says. “Darker hair dyes contain higher concentrations of PPD.”
Hair dye is typically the only type of hair product in which PPD is used. “It can also be found in textile or fur dyes, temporary henna tattoos, dark colored cosmetics, and other products like black rubber and printing ink,” says Mikailov.
Benefits of PPD for Hair
- Extends the life of your hair dye: “It provides a long-lasting hair color and helps protect against fading,” says Chiu.
- Provides natural-looking hair color: “It is a permanent dye that doesn’t come off with shampooing and gives hair natural-looking color,” Mikailov says.
Hair Type Considerations
PPD can be used on all hair types and textures, “however, caution should be used when applying hair color formulas to hair that has undergone different types of chemical services or previously damaged hair,” Yates says.
“Hair and scalp health should all be assessed before applying any hair dye," she continues. "Professional hairdressers are trained to evaluate and formulate accordingly and can use PPD-based formulas as needed to deliver the desired result. It is thought [best] to limit usage to every two to three weeks for consumers, but fixing a color disaster immediately will not necessarily cause adverse effects. It is not so much the dye that is the challenge, but it can be the overall formula that poses hair health risks.”
How to Use PPD for Hair
When using at-home hair color, as always, it’s best to carefully follow the instructions on the box and stick to them. “Always do a patch test on the inner elbow of one arm for a few days if you have sensitive skin,” Chiu says. “If you are concerned about a reaction, you can apply a barrier like Vaseline to your hairline and the tops of the ears. Do not leave hair dye on for longer than recommended, wear gloves, and rinse thoroughly.”
Looking to get into the chemistry of PPD? Yates breaks it down: “PPD is generally mixed with another dye, called a coupler, which is then blended into a hair color base. The hair color base is combined with an oxidizing agent in a ratio of 1 to 1, 1 to 1.5, or 1 to 2. The overall mix is applied to the hair starting at the roots for 10 to 45 minutes, depending on desired results. After processing, the mixture is rinsed thoroughly from the hair and scalp. You will generally follow with a shampoo and conditioner as a final step in the process.”
Those with sensitive skin and scalps should proceed with caution. “PPD is frequently implicated as a cause of scalp contact dermatitis that is due to hair dye,” Mikailov says. “In fact, PPD was the Contact Allergen of the Year for 2006 by the American Contact Dermatitis Society (ACDS). Anyone who develops scalp redness, scaling, or itching one to two weeks after hair dyeing should consult their dermatologist or allergist and get evaluated for a potential PPD allergy.” Hairdressers are at especially high risk for a PPD allergy; Mikailov suggests pros learn techniques to minimize exposure and protective measures while handling hair dye.
There are alternatives to PPD commonly used in the world of hair color. “These alternatives can be less irritating to the scalp while delivering the same coloring benefits,” Yates says. That said, Yates notes that if you're allergic to PPD you could still experience adverse reactions to PPD alternatives; it's best to do a test spot on your arm to make sure. Another thing to note is that hair colors formulated without PPD tend to fade more quickly.
Militello M, Hu S, Laughter M, Dunnick CA. American contact dermatitis society allergens of the year 2000 to 2020. Dermatologic Clinics. Published online April 2020:S0733863520300231.