Can you mix permanent and semi-permanent hair dye?

brown with reddish highlights

Have you ever thought of mixing permanent and semi-permanent dye?


Well, don’t even think of trying it, as it could have disastrous results.

Never mix permanent and semi-permanent dye, because:

  • Both products have completely different chemical makeups. 
  • Semi-permanent and permanent dye work very differently in your hair.


And I would know, because I tried it on my hair.

I was in one of those situations where you just have to use what you have on hand. Let me explain.


I’ve dyed my hair light brown with permanent dye for years.

My sister, on the other hand, uses semi-permanent dye, because she doesn’t want to use products with ammonia or peroxide.


And, since I have short hair, I always use half of the product to dye my hair and save the other half for the next month.

But as I was dying my hair two months ago, I discovered that I didn’t have enough product. Maybe I used a bit more than normal the month before.


But I knew my sister had a semi-permanent dye hidden in the bathroom vanity.

I checked the color, and could have jumped for joy. It was a chestnut brown.


 So, I decided to mix the permanent dye I already had with some of the semi-permanent dye. 

Of course, I could have bought more of the permanent hair dye, but I was in a rush to get ready for a party, and I was leaving in just a few hours.

So, throwing caution to the wind, I mixed the two dyes.


At first, everything seemed to go well.  The color looked the same as it always did, and I went to my party.

But after four shampoos my hair was anything but the even brown I wanted.


 It was brown, but a mix of light and dark brown. 

This can look great if you have some strands lightened on purpose, like a balayage, but when the light strands aren’t placed correctly the difference in color can look like a mess.


And the only explanation I could think of was that I had mixed the two types of dye. When I told my sister what happened, she was practically rolling on the floor laughing.

After her laughter faded, she got serious and explained why exactly mixing permanent and semi-permanent dye is a bad idea.


So, if you don’t want to end up with zebra hair like mine, keep reading, because here we’ll explain why these two products can create a catastrophic combination.


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Why you should not mix permanent and semi-permanent dyes

whitening agent

Permanent and semi-permanent hair dye is like oil and water.

Their chemical compositions is so different that it’s almost impossible to mix them evenly.


  • Semi-permanent dyes are more gentle, don’t contain ammonia and don’t need to be mixed with developer.

It deposits the color on the surface of the hair, almost like adding a coating on the hair.


  • Unlike permanent dye, semi-permanent doesn’t enter the hair shaft, or the cortex, and can’t lighten your hair, cover grays, or permanently change your hair color.

Each product was designed for a different purpose.

So, what does a semi-permanent dye do?


The answer is simple.

Semi-permanent dyes:

  • Deposit color on blond or lightened hair
  • Conceal, but don't completely cover, grey hair.
  • Refresh faded hair color.
  • Tone grey or copper-colored highlight and blend them with the base hair color.
  • Add brightness and shine to dull or damaged hair.


Since this type of dye only affects the outer surface of your hair, it only lasts between four and ten shampoos (depending on the health and porosity of your hair) before it starts to fade.


What about permanent dyes?

They are completely different from semi-permanent colors.


  • Permanent hair dye does exactly what the name suggests: permanently change the color of your hair.

Because of its chemical formula, and the developer that it's mixed with, permanent hair dye open the hair cuticle and deposits the hair dye into the internal part of the hair structure. The cuticle then closes again, sealing the pigment inside.


  • Not only that, but permanent dye doesn't fade, so you can see a difference between dyed hair and new growth.

Permanent dyes can lighten or darken hair, and completely cover grey hair.

But there's one more important difference between these two products.


  • Permanent hair dye changes the hair's structure, so the color doesn't fade.

Basically, permanent dye opens the hair cuticle before depositing the pigment, and semi-permanent dye doesn't.


 Permanent and semi-permanent dyes have incompatible chemical properties, so they don't mix well, just like oil and water.  

While you can mix them, you're not going to get the results you want.

Which is what happened to me.


Because I mixed the two kinds of dye, the permanent dye and developer affected parts of my hair, but not all of it.

The result?


The color faded unevenly, so some stands were a completely different color after a few shampoos.

How did I fix it?



To fix my botched dye job, I ran to the pharmacy and bought a permanent dye, which I used to cover the lighter strands.

The problem?


Since mixing the two dyes didn't work, I had to re-dye my hair in under two weeks.

Which left my hair feeling rather dry. So I treated myself to a deep conditioning treatment.

This reminded me of something.

Anyone remembering learning about the communicative property in grade school?


Let me remind you -because I don't blame you if you don't- it states that no matter where you move the numbers in an addition or multiplication problem, the answer stays the same.

While, hair dye isn’t like math, because no matter how you add or mix permanent and semi-permanent dye, the result is going to change.

Add another type of dye to the mix, and you simply won't get the same results.


So now you know: not only does mixing permanent and semi-permanent dye not work, but you could end up with multicolored hair.

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