Can I straighten my hair after dying it? Does the flat iron change the color of the hair?

straightened dyed hair

  • Ideally, you should wait, at least, two weeks to straighten your hair after dying it. That’s how long it takes for the dye pigments to settle in the hair core.
  • If you get a straightening treatment too soon, meaning less than two weeks after coloring, you could ruin your dye job. Your hair could lighten three or four shades.
  • If you use heat styling tools before two weeks, your hair will lose pigmentation and lighten. If you dyed your hair warm blonde, you may not notice the difference. But if you dyed your hair brown, the color difference will be noticeable.


So, the answer is clear.

You should wait at least fifteen days after coloring to straighten your hair with a professional treatment or a flat iron.

Heat is one of the worst enemies of colored hair.



  • Heat dehydrates your hair. Therefore, your new color will look dull, and your hair will be drier.
  • The heat opens the hair cuticles, and color begins to fade.


 The flat iron can lighten hair color by up to three levels after a fresh dye job. 

If you straighten your hair right after coloring it, the final color will look nothing like the one you applied.

Now, what do you mean when you talk about straightening your hair?


  • Do you mean flat ironing it?
  • Do you mean a professional straightening treatment?


I don’t want to confuse you. But I want to be precise. I imagine many people thinking, “I just want to flat iron my hair. I’m not going to apply keratin or similar treatments.

I’m talking to you too.

Tabla de Contenidos


Even if you just want to flat iron your hair, the heat will change the color of your fresh dye job

dyed hair straightener

Yes, it’ll change your color.

And it might even lighten it up to three levels.


Of course, if you color your hair warm blonde, you may not notice the color difference.

 But if you use cool colors like auburn 4 or medium like dark blonde 6, your hair may actually look orange or red due to color fading. 

Do you know why?


During permanent hair color, the cuticles of your hair open up. Some of them break, and some don’t even close again.

That’s why color-treated hair is more fragile and brittle than unprocessed hair.


Flat irons at temperatures up to 230°C evaporate the color and the water molecules.

 Therefore, if you flat iron your freshly-colored hair, the color will become lighter and your hair will be drier and more brittle. 

Have you noticed that your hair gets lighter under the sun?


Well, now imagine flat ironing your freshly colored hair at 230°C. It’s like 20 days of sun exposure in just 20 minutes.

That’s a lot of heat!


When you rinse the dye out, color settling begins. It’s how long it takes for your hair to absorb all the pigment from the hair dye and take it to the core.

Then, the core begins to expel the excess dye. Therefore, you’ll most likely notice that your color is not as intense as the first day after coloring.


What happens if you use heat tools during color settling?

 When your hair starts to expel the excess, it’ll lose more dye due to the evaporation produced by the flat iron. 


This process takes approximately 15 days. So, I recommend not flat ironing your freshly-colored hair before that.

And if you want to straighten your freshly-colored hair with professional treatments, things don’t get any better.


Straightening treatments ruin freshly colored hair

straighten dyed blonde hair

All professional hair straightening treatments contain chemicals that damage your hair color.

One of them is formaldehyde.


This chemical ingredient penetrates the hair core to change its internal structure. In other words, it “straightens” your hair structure. That’s why your hair feels smoother.

I’ll give you an example to help you understand.

Have you ever seen a metal spring?

Have you ever noticed how difficult it is to straighten it and remove all the twists?


You won’t be able to straighten it with your hands, and you might even hurt yourself trying. That’s why you need tools.

Now, let’s transfer that to hair.


Your hair would be the metal spring, and formaldehyde is the tool you need to straighten it. It’s a powerful chemical that can cause serious damage because its fumes are toxic.

If you’ve ever had your hair professionally straightened, you’ll have noticed the steam from your hair when you flat iron it.

Formaldehyde encapsulates all liquid and semi-liquid molecules of water, proteins, vitamins, amino acids, nucleotides, and pigment.


If you add the heat of the flat iron, all the dye you applied to your hair will disappear due to the straightening treatment.

 A professional straightening treatment should only be applied three to four weeks after coloring if you want to keep your color like the first day. 


Apart from waiting fifteen days to straighten your color-treated hair, you should also take some precautions. And that’s what I’ll talk about next.


How to protect color-treated hair from the heat of the straightener

woman heat protectant spray

I can recommend two types of products:

  • Thermal protectors with UV and UVB filters manufactured by the big brands.
  • Avocado oil, a natural protector.


Thermal protectors are designed to add moisture to your hair. They can be water-based, silicone-based, or creams.

 They are very easy to apply and should always be applied to dry hair before straightening it. 

They have to include UV and UVB filters to protect your colored hair from the heat.


Avocado oil is ideal for your color-treated hair because it protects the color and provides moisture, nutrients, vitamins, shine, softness, and manageability.



To straighten your hair after dying it either with a professional straightening treatment or with a flat iron, you should wait at least fifteen days.

That’s the only way for the color molecules of the dye to settle in the hair core and achieve a vibrant and lasting color.

Deja Tu Comentario