(Tiny Tips) – Hair dyes can add color to hair strands, but can cause hair damage, including loss of hair strength, loss of hair thickness, and other side effects.
We’ve all heard the hair dye horror stories about breakage, dryness, and general signs of damage.
But if hair dye is so harmful to you, why does it make your hair look so good? Here’s what you should know about the link between hair dye and hair health.
What do I need to know about hair dye and hair damage?
Dry hair is about 95% protein. These proteins act like roof tiles, protecting the underlying strands from:
- Humidity
- Hot
- UV rays from the sun
Using permanent or demipermanent hair dye or bleach can cause a chemical reaction that causes these protective proteins to rise, allowing the chemicals to penetrate the hair strands. Hair dye changes the chemical composition of your hair. The result is a change in color.
The process of permanent or semi-permanent hair coloring is different from temporary or semi-permanent hair coloring. Temporary dyes leave color in your hair but usually don’t penetrate deeper (although they can still damage your hair). This goes for alternatives to traditional hair dye, such as Kool-Aid, carrot juice, and even coffee.
Changing the protein structure of your hair through permanent and semi-permanent coloring may cause the following side effects:
- Loss of hair strength
- Your hair is less resistant to heat styling
- Reduced hair thickness
- Increased hair follicle roughness
With this in mind, the hair coloring process essentially changes your hair. The short- and long-term effects depend on your hair structure.
If your hair is already thin or brittle, dyeing it can make it even more brittle. Even if you have thick hair, you may experience side effects when dyeing your hair, as the color may take longer to “boost” hair proteins and may require longer application.
What chemicals should I be aware of?
Here are some chemicals commonly used in hair dye.
Bleach
Bleaching your hair changes the pigments that give your hair its color. A 2020 study found that bleaching may have the following effects:
- Hair strength
- Humidity
- Hair’s ability to withstand heat
The extent to which bleach damages your hair depends on your hair’s pH (or acidity) and may also be affected by the pH of your surrounding environment.
Bleaching is usually done by using hair dye that contains hydrogen peroxide. Hydrogen peroxide is an oxidizing agent. This means it activates hair color, but the oxidation process causes damage.
Henna
Henna is a natural semi-permanent hair dye. However, “natural” does not mean less harmful.
A 2019 study found that henna dye can damage hair, causing it to become thicker and more brittle. If henna dye is left on for more than an hour, it can cause damage similar to that of bleach.
Henna can also cause contact dermatitis and skin irritation, especially if you are allergic to any compounds or ingredients in the henna ink.
P-Phenylenediamine
Paraphenylenediamine (PPD) is a compound commonly found in hair dyes that requires an oxidizing agent such as hydrogen peroxide.
Some people report allergic reactions occurring more frequently due to PPD hair dye.
Does it matter if the dye is light or dark?
If you want to lighten your hair, the more times you bleach it, the more damage it will do to your hair.
A 2019 study used microscopic techniques to examine bleaching levels and found that hair fibers were most damaged by long-term bleaching, especially the type needed to transform dark hair into lighter hair. For this reason, many hair color experts advise against going too light in one go.
Going from light to dark is not necessarily less damaging, as it still changes the hair structure. Taking care of dark hair is also important.
How to repair damaged hair?
Hair damage from heat styling or excessive coloring procedures increases the likelihood of further hair damage.
Here are some ways to protect your hair:
- Use hair dye with conditioning products. The conditioner in hair dye helps minimize the amount of hair damage. One example is hydrolyzed silk proteins.
- Limit heat styling. Heat styling can further weaken your hair. Limit the use of thermal styling tools such as:
-
- Hair dryer
- Curling iron
- Iron
- Use a heat protection spray or lotion. Apply it to your hair before heat styling.
- Allow some time between hair color appointments. Dying your hair less frequently can help minimize damage.
- Use a moisturizing shampoo and conditioner. These products help your hair retain moisture after color treatment. Strongly scented shampoos that contain lots of detergent (and often lots of lather) tend to be more harmful.
- Choose shampoo, conditioner, and other hair care products in specific colors. These are designed to help protect color-treated hair.
- Consider dying your hair to a more natural color. This helps limit the damage if possible.
Allergic reaction to hair dye
In rare cases, hair dye can cause severe allergic reactions.
Swollen lips and eyes are early signs of an allergic reaction. If you have difficulty breathing after dyeing your hair, seek emergency medical attention.
Before dyeing all of your hair, you can perform a “patch test” by applying hair dye to a small area. Keep in mind that not everyone who is allergic to hair dye will react to the patch test.
Are there natural alternatives?
There are "natural" plant-based hair dyes (see henna above). It's important not to think of them as completely hair-friendly - they can still cause changes in the hair, making it less strong, and can also cause allergic reactions.
Another trend is "organic" or "eco-friendly" dyes. The U.S. Food and Drug Administration (FDA) states that “organic” dyes are not necessarily safer than non-organic dyes. Although they may be obtained through different methods, organic dyes do not necessarily mean they are safer.
Take it away
Hair dye can cause hair damage. Using hair care techniques like limiting heat styling and conditioning your hair can help minimize damage. Dying your hair closer to its natural color will also help reduce the time your hair is exposed to hair dye and minimize damage.
If you’re concerned about the health of your hair, talk to your stylist about using conditioner or other methods of coloring to keep your hair looking and feeling healthy.