Dec. 16, 2025 — If you search for hair dye on social media, you’ll mostly see inspo photos of women with brightly colored locks. But you’ll also find clips warning you that dying your hair isn’t so fun — it could cause cancer or reproductive health problems.
If you’re one of the up to 80% of women in the U.S. who color your hair, you might see these headlines and wonder: What’s really in my hair dye, and is it safe to use?
“There's still a lot that we have to learn, but the data that exists so far, I think, is enough for us to be worried about what we're being exposed to,” says Samantha Schildroth, PhD, MPH, a postdoctoral associate in environmental epidemiology at Boston University.
How Risky Is Hair Dye?
The concern with hair dyes isn’t what they do to your hair — it’s what happens when they enter the skin around it.
“The scalp has a very rich blood supply,” says Melanye Maclin, MD, a research and development dermatologist. “Those chemicals absorb into the scalp and enter the main bloodstream.”
In fact, hair dye users have significantly different levels of at least 11 metabolites circulating in their blood compared to those who don’t use it, according to research published in Scientific Reports.
What does that mean for your health? It’s hard to say for sure because there are no clinical trials that prove that one product or another increases risk. However, cohort and case-control studies have shown associations between hair dye use and some negative health outcomes.
A recent study review of 96 articles suggests that women who use permanent or semi-permanent hair dye just once or twice have a 7% increased risk of breast cancer, while those who use it 35 to 89 times have a 31% increased risk. Permanent dye was also associated with a 250% increased risk of bladder cancer in people with certain genetic factors.
“There can be health risks with using these chemicals, especially if you’re continually exposing your body to them over time,” says Maclin. “It’s a progression.”
Permanent dyes penetrate hair to its middle layer — the cortex — to strip existing pigment and leave new color behind. Semipermanent and temporary dyes tint the outer layers of the hair and wash out over time.
Researchers point to aromatic amines in permanent dyes, chemicals that help hair color stick to your strands, as potential culprits that might increase cancer risk. These substances can bind to DNA and lead to cancerous mutations. They can also affect reproductive health by mimicking or blocking the sex hormone estrogen.
A recent cohort study from Schildroth’s research group suggests that women who use hair dyes might have an increased risk of uterine fibroids, which are noncancerous growths that can cause pain or reduce fertility. Black women who used temporary hair color rinses the past 12 months had a 98% increased risk of fibroids.
“Fibroids are typically very responsive to estrogen, so if you have a chemical that mimics estrogen in the body, it could then, in turn, influence the way fibroids grow and develop in the body,” she says.
Schildroth also notes that temporary hair colors are usually thought to be safer than permanent dyes, since they contain fewer aromatic amines. However, her study’s results raise questions about their safety.
Are Modern Hair Dyes Safer Than Older Products?
Some of the research on hair dye safety dates back decades, so you might assume it’s out of date. But the main ingredients have not changed.
There’s been some progress, however. Before 1980, dyes contained several carcinogenic aromatic amines that have since been phased out, but some, such as suspected carcinogen p-Phenylenediamine (PPD), are still found in modern formulations.
More change could be on the way. A bill introduced in the U.S. House of Representatives proposes banning m-Phenylenediamine, o-Phenylenediamine, and 13 other potentially harmful ingredients from personal care products.
However, that doesn’t mean the chemicals that replace them will be safer, says Schildroth: “Unfortunately, within the industry and within our field, we see what we call chemical whack-a-mole, which is pretty common, where if you have one chemical that's been banned or phased out voluntarily by industry, it’s typically replaced by another chemical that could be just as toxic, if not more toxic.”
What’s the Safest Way to Use Hair Dyes?
Knowing which hair dyes are safer than others is not easy. “We can't really point and say this is the particular type of dye that is really bad that we should avoid,” Schildroth says. Studies are often based on surveys about hair dye use, and they don’t drill down to exactly which brands or formulas users applied.
However, there are steps you can take to lower potential health risks.
Read the labels on your products. Look for hair dyes without PPD or other aromatic amines, such as m-Aminophenol. Plant-based or vegetable dyes often contain fewer of these substances, says Maclin. She also recommends looking for products free of sensitizing ingredients such as ammonia and sodium lauryl sulfate.
“The Environmental Working Group has an online database where they go through products and give them scores based on the ingredient lists,” says Schildroth. “That's a really great resource for consumers who are trying to stay up to date.”
Go longer between applications. Research suggests that the potential health risks of hair dye are highest for cosmetologists who color other people’s hair for a living. But even for consumers, more frequent use of hair dye can be associated with more risk. Consider extending the interval between touch-ups, and don’t change your color frequently on a whim. Schildroth’s research found a higher risk of fibroids in women who used multiple hair dye products.
Cover your scalp and hands. Maclin recommends coating your scalp in a thin layer of petroleum jelly before applying hair dye. Also wear gloves. The goal is to reduce the amount of dye that gets absorbed through your skin and travels into your bloodstream.
Don’t use dyes with other hair treatments. Research suggests that using hair relaxers along with hair dyes might increase cancer risk. Relaxers can contain a wide range of cancer-causing and endocrine-disrupting substances. If you’re not ready to give these treatments up, at least space them out.
“You're only supposed to do a hair relaxer maybe every six to eight weeks, and the same thing for hair dyes, but because we have these over-the-counter, easy-to-access products, there are women doing it every two weeks, and that’s upping the risk,” says Maclin.
Don’t add color to synthetic hair. A recent Consumer Reports investigation showed that some synthetic hair braids contained benzene, a known carcinogen. Adding hair dye could compound the problem, Maclin says.
Don’t start too early. Maclin sees a lot of teenagers coloring their hair, and she’s concerned about their future reproductive health and cancer risk. Try to steer kids and teens away from hair dye to avoid exposure to chemicals that can mimic or block estrogen while their reproductive systems are still developing, she suggests.
