Fun fact: Coloring the hair isn’t a recent fad. In fact, people were still using natural pigments and even leeches to color their hair as far back as 1500 BC.
With the cosmetic industry coming in the line of fire every now and then for the possible harmful effects of the chemicals used in cosmetic products, you may also want to know how safe your hair dye is. Whether you want to cover your grays or add highlights, lowlights, go lighter or darker, it’s essential to know what your “hair color” or “hair dye,” often used interchangeably, really entail. Depending on how long they last, hair dyes are broadly classified into:1
- Permanent (coal-tar dyes or oxidation dyes): This lasts about 8–10 weeks. It contains ammonia, which opens up the cuticle of the hair, hydrogen peroxide which oxidizes the pigment (melanin) in the hair to bleach it – also known as the developer – and a colorant like paraphenylenediamine (PPD) or paratoluenediamine (PTD) that imparts the desired color. The amount of hydrogen peroxide required to bleach depends on your natural hair color. The darker it is, the more peroxide you need to bleach it.
- Demi-permanent: This lasts for around 6 weeks. It opens up the hair shaft partially but does not contain enough hydrogen peroxide to bleach or “lift” the hair.
- Semi-permanent hair dye: This lasts up to 6 weeks. It does not contain ammonia or a developer, so your hair is not bleached. But it may still contain PPD or PTD which deposit the color partially into the hair shafts.
- Temporary hair dye: This lasts only until the next couple of washes at best. The colors do not penetrate the shaft and only sit on the surface of your hair, outside the cuticle. However, if your hair is damaged, some of the colors may seep in.
Here are some of the possible side effects of hair dyes, listed in the order of benign to sever.
1. May Cause Skin Discoloration
Skin and nails are made of the same type of keratinized protein as hair. Which is why any kind of slips during the coloring process can result in patches of discolored skin, especially around the hairline. This is more likely to happen to people with dark or dry, absorbent skin. However, this shouldn’t be a massive cause for concern since your skin should be back to normal in a few days to a week, as the skin naturally renews itself and the top layer of your skin is removed.
To avoid this from happening in the first place, apply a thin layer of vaseline or any oil on your hairline before coloring. Be sure to wear latex or nitrile gloves if you’re coloring your hair yourself.2
2. Affects Hair Quality
While semi-permanent dye is a gentler option than permanent dye, one tends to use it repeatedly, leading to damage in the long term. Temporary dye is the least intrusive of the lot, but make sure you condition your hair well before using it.
Regular use of hair dyes, especially the permanent type, can render your hair brittle and over-processed. During hair coloring, ammonia raises the pH of hair and opens up the scales in the cuticle so that the color molecules enter the next layer, the cortex. Here, through a chain of chemical reactions, hydrogen peroxide bleaches the hair and the color pigments join together to settle down on the cortex. The cuticle closes when you then rinse the hair.
First, the process of raising the cuticles artificially is the first step in hair damage since that lets the moisture escape. Second, hydrogen peroxide bleaches your hair and further dries it out. Moreover, if you happen to use more hydrogen peroxide that necessary or leave the color in for longer than instructed, there’s greater damage. There is also a possibility of free radical damage. Frequent coloring will eventually lead to dull, dry, and brittle hair and even hair loss.3
New advances in hair coloring technology, however, have come up with ammonia-free products that are not only easier to use and less damaging but also fight free radical damage.4
If you want to get a permanent hair color, it’s best to avoid a box kit. Visit a professional salon. If you do use a box kit, look for ammonia-free products with a hydrogen peroxide volume less than 40. Also remember to condition your hair well before coloring it so that you don’t lose too much moisture.5
3. May Cause Allergies
Exposure to ammonia and PPD can cause rhinitis or asthma-like throat irritation as well as coughing and wheezing. Even higher exposures can lead to fluid buildup in lungs and might lead to lung damage. Hair stylists and colorists might develop asthma as well.6
Allergic reactions to hair dye are fairly common because PPD, a colorant, is a common allergen affecting around 1.5% of the population. People prone to contact dermatitis may be especially likely to develop an allergic reaction to the PPD. You mat experience itching or a swelling in the eyelids or near the ears. But in rare cases, PPD may also trigger an anaphylactic shock, a life-threatening allergic reaction.7 8
However, for the majority of the population, PPD levels in hair products are not concerning. The FDA and the European Commission mandate that only a very low and safe percentage of PPD (2%) may be used in hair dyes, and these products need to carry a cautionary note and clear usage instructions. Since PPD does not accumulate in the body, subsequent uses of hair dyes are not risky.9 10
If you have an allergy to PPD, you could opt for a hair dye with PTD. Though these are structurally similar, in a study, 57% of the participants who were allergic to PPD could tolerate PTD well. That said, the researchers point out that they might still be allergic to other ingredients found in hair dyes and may even develop a cross-sensitization allergy later.11
Watch out for PPD in temporary tattoo inks, also marketed as black henna. The FDA advises against using PPD on skin. Not only may the reaction be severe, you may also develop a cross-sensitization to hair dye.
As a safety precaution, always perform a patch test 48 hours before coloring your hair. Instructions that come with the box of hair dye will usually recommend that you apply a small amount of the hair color solution to the inside of your elbow. You need to allow it to dry and see if you develop any allergic reactions, including rashes, itchiness, itchy eyes, pink eye, swollen eyes, wheezing, and nausea.12
3. Might Affect Fertility
While this might seem bizarre, hair dye can cause fertility problems in both men and women. A recent study found that thanks to their constant exposure to chemicals found in hair products (including hair dyes), hairdressers are more likely to have a reproductive disorder.13 One chemical that could be held responsible is lead acetate, which is found in progressive or gradual hair dyes that require multiple application.14 The FDA maintains that the level of lead acetate found in hair dye is not sufficient to cause a lead buildup in the body. However, it’s mandatory for hair product manufacturers to provide a cautionary note for all products containing lead acetate.15
4. Might Cause Cancer
In the hair dyes marketed before 1980, some amines were found to cause cancer when tested on animals. In the 80s, hair color manufacturing companies got rid of these to make hair color safer.16 A few types of cancers and their links have been explored in studies on animals, or on isolated human cells, or observational studies on a certain group of people, but there seems to be no definite answer.
- Bladder cancer: Hairdressers and barbers who use hair dyes on a daily basis for 10 years or more may have a higher risk of developing bladder cancer, but personal use does not seem to be linked with bladder cancer, except in some subgroups of women with a particular genetic build.17 18
- Non-Hodgkin lymphoma: Some research studies have established a relationship (not necessarily causal) between using hair color and the likelihood of developing non-Hodgkin lymphoma, especially in women who used dyes before 1980 or chose darker colors.19 20
- Leukemia: Researchers have also found some evidence to suggest that long-term use of permanent hair color can possibly make one more likely to develop adult acute leukemia.21 But other studies have not supported these claims.
- Breast cancer: Research also does not indicate a relationship between hair color and breast cancer.22
- Multiple myeloma: While a 1994 study found that women who used black hair dye for more than 20 years had a slightly increased risk of dying from multiple myeloma, subsequent studies failed to find any link.23
Because of these mixed results, the scientific community remains largely ambivalent on whether hair color can be categorically said to be linked with various types of cancer. The National Toxicology Program holds that some chemicals used in dyes are carcinogenic and while the International Agency for Research on Cancer (IARC) holds that occupational exposure to hair dyes is “probably carcinogenic to humans,” it does not consider personal use risky.
The Food and Drug Administration notes that hair color manufacturers are no longer using the two key chemicals that were found to have carcinogenic properties back in the 70s and 80s and that it does not have enough “reliable evidence” to establish a definitive link between hair color and cancer.24 At most, there is a “very minimal” link between modern hair color and the risk of developing cancer.25
Safety Precautions To Take While Dyeing Hair
Research may still be on the fence about the health impact of hair dyes. But you can play it safe by not overusing hair dyes. For instance, reduce the frequency of dyeing your grays if you are unwilling to cut it out altogether. Always read the label and choose a product low in ammonia and hydrogen peroxide, and make sure you follow these safety precautions.
- Always strictly follow the instructions outlined on the hair color product packaging.
- Perform a patch test 48 hours before the application, especially if you’re coloring your hair for the very first time or trying a new brand. In fact, with the constant modifications in ingredients, a patch test is a good idea every time!
- Keep the color solution away from your eyes, and always wear protective gloves.
- Don’t leave the color solution on your hair longer than directed on the packaging.
- Don’t color your hair if your scalp is itchy or sunburned.
- Never use hair color on your eyelashes or eyebrows. This can be very harmful to your eyes and you even risk going blind.26 27
Coloring Hair During Pregnancy
Many women are hesitant to color their hair during pregnancy or immediately after childbirth due to the presence of so many chemicals in hair color. The American Pregnancy Association, however, maintains that chemicals found in permanent and semi-permanent hair color are not really toxic and that there’s no harm in using hair color while pregnant. In addition, only very little dye is absorbed by your skin and even less is actually likely to reach the unborn baby. The same also holds true for breastfeeding. There is little to no chance of hair color chemicals entering your bloodstream and contaminating your milk supply.28
That said, due to the possible risks associated with exposure to chemicals in hair dye, many OB/GYNs recommend that you wait until the end of your first trimester to color your hair.29 To be safe, always check with your OB/GYN and avoid if you can.
Natural Alternatives To Chemical Hair Dyes
If all this talk about chemicals has you worried about what you’re subjecting your mane to, don’t worry. There are plenty of natural ways to tint your hair that don’t involve harmful chemicals.
- Henna: This has been used for centuries by women in Asia to add a reddish, burgundy hue to hair. Henna also conditions your hair and leaves it luxuriously soft. With regular use, your hair becomes naturally henna-colored, which can work well if you have dark brown hair.
- Lemon juice: This can help lighten hair if that’s your goal.
- Chamomile tea: This can help add natural highlights.
- Black tea and coffee: When brewed, cooled, and then applied, this can help make hair darker.
|↑1||What’s That Stuff? American Chemical Society.|
|↑2||Hair Coloring I. University of Houston.|
|↑3||The facts about…PPD and hair colorants. The Cosmetic, Toiletry & Perfumery Association Limited.|
|↑4||Scientists Develop the First Significant Advance in Hair Dye in 50 years. Wired.|
|↑5||Carlson, Karen J., Stephanie A. Eisenstat, and Terra Diane Ziporyn. The new Harvard guide to women’s health. Vol. 1. Harvard University Press, 2004.|
|↑6||Accute and Chronic Health Effects of Chemicals. Rutgers, The State University of New Jersey.|
|↑7, ↑12||Hair dye reactions. NHS.|
|↑8||Allergy to paraphenylenediamine. DermNet NZ.|
|↑9||The facts about…PPD and hair colorants. The Cosmetic, Toiletry & Perfumery Association Limited.|
|↑10||Hair Dyes. U.S. Food and Drug Administration.|
|↑11||Scheman, Andrew, Christina Cha, and Manpreet Bhinder. “Alternative hair-dye products for persons allergic to para-phenylenediamine.” Dermatitis 22, no. 4 (2011): 189-192.|
|↑13||Kim, Dohyung, Mo-Yeol Kang, Sungyeul Choi, Jaechan Park, Hye-Ji Lee, and Eun-A. Kim. “Reproductive disorders among cosmetologists and hairdressers: a meta-analysis.” International archives of occupational and environmental health 89, no. 5 (2016): 739-753.|
|↑14||What to Look Out For. The Pennsylvania State University.|
|↑15||Lead Acetate in “Progressive” Hair Dye Products. FDA.|
|↑16||Hair Dyes and Cancer Risk. National Cancer Institute.|
|↑17||Harling, Melanie, Anja Schablon, Grita Schedlbauer, Madeleine Dulon, and Albert Nienhaus. “Bladder cancer among hairdressers: a meta-analysis.” Occupational and environmental medicine 67, no. 5 (2010): 351-358.|
|↑18, ↑25||Cancer Myth: Hair dyes and cancer. Cancer Council Western Australia.|
|↑19||Zahm, Shelia Hoar, Dennis D. Weisenburger, Paula A. Babbitt, Robert C. Saal, Jimmie B. Vaught, and Aaron Blair. “Use of hair coloring products and the risk of lymphoma, multiple myeloma, and chronic lymphocytic leukemia.” American Journal of Public Health 82, no. 7 (1992): 990-997.|
|↑20||Hair Dyes. American Cancer Society.|
|↑21||Rauscher, Garth H., David Shore, and Dale P. Sandler. “Hair dye use and risk of adult acute leukemia.” American journal of epidemiology 160, no. 1 (2004): 19-25.|
|↑22||Hair Dyes And Breast Cancer Risk. Susan G. Komen.|
|↑23||Study of Hair Dye Finds No Association of Myeloma Risk in Women. The University Of Albany.|
|↑24, ↑26||Hair Dyes. US Food and Drug Administration.|
|↑27||Hair Dyes. American Cancer Society.|
|↑28||Hair Treatment During Pregnancy. American Pregnancy Association.|
|↑29||Fertility FAQs. University of California Los Angeles.|