The most common skin reaction to hair dye is contact dermatitis — a skin irritation that occurs after touching a substance you’re sensitive to.[7] With contact dermatitis, you may notice skin discoloration, itchiness, and swelling, explains Levine. “In severe cases, you may also see scaly skin,” she adds. 
These symptoms usually appear on the scalp, face, and neck, as these areas are most likely to come into contact with the dye.[8] However, if you don’t use gloves when applying DIY dye, you may also experience these symptoms on your hands, Levine says.
Additionally, when your skin’s protective barrier is damaged, hair dye can easily get through and cause skin irritation or sensitivity. For example, eczema can result in tiny breaks in the skin’s surface, allowing hair dye ingredients to potentially cause irritation. Similarly, the ingredients in hair dye can also aggravate scalp psoriasis, a condition where patches of thick, raised skin develop on the scalp. 

However, skin issues aren’t the only concern with hair dye. Your eyes may become irritated if they come into contact with the product. And the fumes from hair dyes containing certain ingredients, such as ammonia or formaldehyde, can cause difficulty breathing, says Levine. 

Can Hair Dye Cause Cancer?
We’re still not clear on cancer risk from hair dyes, says Daniel Landau, MD, an oncologist at the Medical University of South Carolina in Charleston. The main concern around hair dyes potentially causing cancer has to do with semi-permanent and permanent dyes, particularly darker dyes, which have more chemicals than the others, Dr. Cohen explains.

Scientists have studied the link between hair dye and cancer for years. Some research suggests an association between hair dye and cancer, while others have not found these links. 

For example, research from 2011 found a possible connection between using permanent hair dye and an increased risk of bladder cancer.[9] But results from a 2020 study did not find any link between the personal use of permanent hair dyes and the risk of most cancers or cancer-related deaths.[10] 
Beyond the mixed findings, studies around hair dye often have limitations that could impact the results. Products are so varied and contain so many ingredients that studying them becomes challenging, Cohen says. 

In addition, there are different types of exposure to hair dye. One is personal use, such as dying your hair yourself at home or getting your hair dyed. The other is occupational exposure, which includes hairstylists and barbers who work around hair dyes regularly.[1] This difference must be taken into account when looking at studies, Cohen adds. 
Hair Dyes Have Changed
Experts think the aromatic amines in hair dyes made before the 1980s are the likely culprit behind any increased cancer risk observed in research studies from that era.[11] Aromatic amines were found to cause cancer in lab animals. Those same amines are also found in diesel fuel and cigarettes, says Dr. Landau. 
But hair dyes have changed over time. Since the late 1970s, hair dye manufacturers have eliminated the use of some of these potentially harmful chemicals.[11]
Recent Study Findings Are Still Mixed
In 2010, the International Agency for Research on Cancer warned that some chemicals professional hairdressers use daily are potentially cancer-causing, particularly increasing the risk of bladder cancer.[12]
A study published in 2019 found that women who regularly used permanent hair dye in the year leading up to the study were 9 percent more likely to get breast cancer compared with women who didn’t use hair dye. For Black women, using permanent dyes every five to eight weeks or more was linked to a 60 percent higher risk of breast cancer.[13]
The same study didn’t find a significant association between breast cancer and semi-permanent or temporary dye use. Yet researchers noted a link between nonprofessional use, such as at-home kits, of semi-permanent dyes and breast cancer risk.[13]
Recent studies looking at the connection between hair dye and cancer risk have continued to show mixed results, Cohen says. 

There is currently not enough evidence to prove that the chemicals in modern hair dye cause cancer in people who get their hair dyed. Still, Cohen adds that a thorough review of the ingredients in these products and the risks involved in using various hair dyes is needed.

Is It Safe to Dye Your Hair When Pregnant?
So far, there’s no significant proof that hair dyes affect fertility or pregnancy, according to the American College of Obstetricians and Gynecologists.[14]
However, data about how hair dyes might affect pregnancy is also limited, as pregnant people are usually not included in clinical trials due to ethical reasons.[15] That said, animal studies have not shown that hair dyes are associated with an increased risk of serious birth defects, says Robert Roman, MD, assistant clinical professor in the Department of Obstetrics and Gynecology at the David Geffen School of at UCLA in Santa Monica, California.
According to Dr. Roman, certain chemicals found in some hair care products, known as endocrine-disrupting chemicals (EDCs), have been associated with infertility and problems during pregnancy. EDCs can interfere with how the reproductive system, brain, and metabolism work.[16] These chemicals might increase the likelihood of certain types of cancer.[17]
Roman recommends avoiding personal care products that contain EDCs, such as phthalates, parabens, and triclosan, before and during pregnancy when possible. “Opting for fragrance-free products can also be helpful to reduce EDC exposure and is better tolerated in people with certain skin conditions or sensitive skin,”" he adds. 

Tips for Safely Coloring Your Hair
The health risks associated with hair dye are not always clear. The good news is that you can take steps to reduce your exposure to potentially harmful chemicals if you want to color your hair, these tips can help you do so safely.

Choose Hair Dye Products Wisely
Vegetable-based hair dyes are generally considered safer alternatives to chemical dyes, says Cohen. These products use plants or other natural ingredients like henna, senna, or cocoa — but they might not provide as dramatic of a color change. And vegetable-based hair dyes may still contain some of the same chemicals found in permanent dyes, like PPD, so read the label carefully before buying.[1]
Temporary hair dye can be another option to consider. It typically doesn’t last as long as permanent dye, but it may contain fewer irritants. It’s still important to pay attention to the ingredient list and look for hair coloring products that are free of potentially problematic ingredients, such as PPD. 

“If you have a preexisting skin condition, or even just have sensitive skin, I would recommend looking for hypoallergenic products,” Levine says. Hypoallergenic products do not contain ingredients that are known to cause allergy. These are usually free of parabens, ammonia, and PPD, she adds.

You should also check the ingredients list to make sure the product doesn’t contain anything that has caused problems for you in the past.[4]
Do a Patch Test 
Experts recommend doing a skin patch test before using any new DIY hair dye product. A patch test checks if you’re allergic to a product by applying a small amount to your skin. 

Here’s how to do a patch test at home to check for hair dye allergy, according to Levine:

Follow the instructions on the box to mix a small amount of hair dye.
Apply a quarter-size amount of dye to a small spot behind your ear or on your inner elbow.
Leave it on the skin for 48 to 72 hours without washing it off.
If discoloration, itching, or swelling occurs in the test area, wash the product off immediately and avoid using the dye.
If there is no reaction, it’s likely safe for you to use.
Levine says to consult with a dermatologist who can perform a more thorough patch test if you have a preexisting skin condition or are unsure about your skin sensitivity.

Take Precautions With DIY Hair Dye
Here are some general guidelines to follow when using DIY hair dye products:[4]
Read and follow the instructions on the hair dye package carefully.
Avoid getting hair dye in your eyes — never dye your eyebrows or eyelashes, as any issues can cause serious eye damage or even blindness.
Wear gloves when applying hair dye to protect your hands.
Work in a well-ventilated area to minimize inhaling any harmful fumes from the hair dye products.
Set a timer and stick to the recommended time on the package for leaving the dye on your hair. 
Rinse your hair and scalp thoroughly after.
If you have psoriasis, eczema, or another skin issue on your scalp, avoid coloring your hair when you have flare-ups of those conditions. Applying hair dye when your scalp is already irritated and inflamed can further aggravate those sensitive areas.

Similarly, don’t dye your hair if your scalp is irritated, sunburned, or damaged. If you’ve recently bleached, relaxed, or permed your hair, wait at least two weeks before using hair dye. And avoid scratching or brushing your scalp for three days before using hair dye.

Consider Not Using Hair Dye in the First Trimester of Pregnancy
Dying your hair during pregnancy is a personal decision, but it’s a good idea to talk to your doctor first. 

Some pregnant people may avoid using hair dyes during the first trimester of pregnancy, Roman says. That’s because the first trimester is a critical time for the baby’s organ development.[18]
Try Dying Your Hair Less Frequently
“Currently, there is no universally accepted recommendation for hair dye users regarding how often or for how long using hair dye will impact their cancer risk,” says Cohen. 

But if you’re concerned, think about spacing out your coloring sessions as much as possible. The less often you expose yourself to hair dye chemicals, the lower your overall risk may be.

Talk to Your Doctor 
Before reaching for the hair dye box, talk to your healthcare provider, especially if you have a preexisting skin condition or are pregnant. 

A dermatologist can identify any potential allergies to ingredients and steer you toward safer hair dye options. If you’re pregnant, an ob-gyn can help you weigh the pros and cons so you can make an informed choice about using hair dye during pregnancy.

The Takeaway
Research on the link between hair dyes and health issues like cancer and reproductive effects has shown mixed results. Hair dye manufacturers have stopped using some of the ingredients that were found to cause cancer in animals. But there are still some potential risks to be aware of — especially with darker, permanent hair dye formulations. 

To minimize your risk, consider using safer alternatives like vegetable-based dyes, and talking to your doctor, especially if you’re pregnant or have a preexisting skin condition. Taking precautions like doing patch tests, using gloves, and ensuring proper ventilation can also help reduce exposure to harsh chemicals and protect your health.