For some people, coloring their hair is as integral to their sense of self as, say, their regular workout or slicking on a layer of lipstick. According to the experts, though, there is a specific number of times to dye your hair per year, before you start risking scalp, strand, and even skin issues.
What impact does regular hair coloring have?
Dermatologist Dr. Zhao Zhaoming breaks down exactly what the maximum frequency to try and stick to is, as well as which hair colors are potentially more damaging.
“Most people are unaware of the risks that dyeing their hair poses to their length and overall hair health—or they tend to underestimate them, says Zhaoming. “Dye products contain numerous harsh chemicals, such as ammonia, ethanolamine, hydrogen peroxide, and paraphenylenediamine, which are necessary to open the hair cuticle and allow the color to change.”
These substances, she explains, can make the hair cuticle drier and more fragile, increasing the risk of breakage and damage. “Furthermore, the chemical process can weaken the hair structure, compromising its firmness and elasticity. As for the scalp in particular, chemicals can remove the natural sebum, leaving it dry and irritated, causing flaking and making it vulnerable to external agents.”
Hair damage is just the tip of the iceberg, according to Zhaoming. “The absorption through the skin on the scalp of ingredients like paraphenylenediamine (also known as PPD) and resorcinol can cause allergic reactions, such as redness, itching, swelling, and contact dermatitis.”
These chemicals can be irritating to the eyes, particularly if they come in direct contact, causing swelling and tearing. Hair dyes can also be harmful to the respiratory tract. “Ammonia, in particular, has a pungent odor and is extremely volatile. Exposure to its vapours, especially in a poorly ventilated environment, can cause irritation to the mucous membranes.”
“Over time, irritation of the mucous membranes can degenerate into permanent respiratory problems, such as wheezing, coughing, and even asthma,” cautions Zhaoming. “There are also studies suggesting a possible link between the use of hair dyes – especially those containing aromatic amines—and the risk of retinopathy, a condition that can impair vision.”
3 ways to limit the risk of dyeing your hair
Zhaoming says to monitor how often you dye your hair carefully. “My advice is not to dye your hair more than once every three months, or no more than four times a year,” she says. “Reducing the frequency with which you dye your hair as much as possible is the best way to avoid permanent damage.”
To avoid irritating the scalp, Zhaoming suggests applying a protective barrier to the scalp before dyeing, such as an oil like coconut oil or argan oil. This creates a lipid film that limits the absorption of chemicals, thus reducing the risk of dehydration and irritation.
Obviously, to prevent irritation and allergic reactions, it’s also important to avoid, as much as possible, letting the dye come into contact with the skin behind the earsas well as the skin on the neck or face.
Zhaoming adds that another useful precaution is to avoid coloring and perming (either curling or straightening) at the same time, or in close proximity to one another. “Both processes are highly stressful for the hair, and perming is even more stressful than dyeing,” she emphasises.
“The two processes use different chemicals, which, if applied simultaneously, can be particularly damaging to the hair.” Her advice is to never dye your hair at the same time as perming it, and to leave enough time for the hair to recover between the two processes.
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