4 hair protein treatment’s side effects (that almost nobody tells)

hairdresser sealing protein treatment

  • To avoid the side effects of protein treatments, the first thing you should do is to respect the frequency of application.
  • If you’re going to apply a protein treatment in the salon, you can repeat it at most every six months according to the treatment type. Alternatively, if you use a home treatment, you can do it every fifteen days.
  • The most common side effects of protein treatments are hair weakness and breakage, frequent greasiness, and skin, eye, and throat irritations.


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All cosmetic products can trigger side effects. The same goes for medications.

Have you ever read the package insert of syrup or oral tablet?


It’s usually longer than the Bible. By the time you’ve finished reading it, you’re convinced that, in the end, the drug will bring you more trouble than anything help.

However, the pharmaceutical industry has to cover itself.

Now, what can go wrong when you use a protein treatment?


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I’ll tell you that the positive aspects outweigh the negative ones. Yes, breathe.

 Tthe negative effects that can be triggered by a protein treatment are actually related to inappropriate application or excessive use. 


So, the protein treatment will have no side effects on your hair if a professional performs it in a salon.

Most protein treatments are applied with heat to ensure that the nutrients penetrate inside the hair and seal the cuticles.


 That’s my first recommendation if you want to avoid the side effects of protein treatment: go to a salon. 

Then, my second recommendation is not to abuse these treatments. Too much protein causes hair weakness or breakage.


My recommendations are based on facts. You can take them or leave them.

If you take them, you’ll avoid the side effects. If you disregard them, here are some of the possible scenarios for your near future.

These are the side effects of protein treatments that you may face.

Tabla de Contenidos


Hair breakage after a protein treatment

This is not a piece of cake. We’re talking about breakage that leads to hair loss.

As you may know, most protein treatments are applied with heat. Then, the cuticles are sealed with a flat iron.

That extreme heat can dry out your hair and cause more damage.


These types of treatments contain formaldehyde, which is a chemical that fills the cuticles and eliminates frizz.

However, at the same time, they dehydrate the hair because they remove water molecules.


 That’s why I recommend applying a protein treatment at the salon. 

Another side effect of formaldehyde is stiffness. It causes the hair to become stiff. Also, if you mishandle the product, you’ll cause hair breakage.


Hair weakening

side effect of protein treatment

Too much protein is bad for your hair.

When you apply the protein treatment, your hair starts absorbing the product and gets stronger. However, if you continue applying protein, your hair won’t assimilate such an amount of nutrients, and will start to weaken.

In short, the effect of the proteins is diluted.


 This is why you shouldn’t abuse this type of treatment. 

If you apply them at home, without heat, you can use them at least once a fortnight.

On the other hand, if you go to a salon, ask the stylist what type of protein treatment is best for your hair and how often you can apply it.

Some protein treatments are applied every three months, such as keratin. Others should be applied every six months.


Protein treatments can cause hair to become greasier

Protein treatments not only penetrate the inside of the hair. They also coat the outer part called the cortex.

The cuticles are in the cortex. They’re small scales that open to absorb nutrients, hair dyes, or expel color during bleaching.

When hair is dry, the cuticles break, and the inside of the hair is exposed. As a result, the hair is ruined, and frizz appears.


Protein treatments fill in these gaps and are sealed with heat, which provides a protective film.

So far so good, and no side effects. However, when you sweat, the scalp expels toxins, dirt, and oil. The hair absorbs this oil to hydrate and be healthy.

When you apply the protein treatment, those processes become limited. So, the oil builds up faster, and your hair will start to look very greasy.


 Unfortunately this is a side effect that appears in 95% of women who apply the protein treatment. 

The only way to solve it is to wash the hair. And here’s the dilemma.


If you wash your hair every day, you’ll fade the protein treatment faster. However, you’ll also damage it because hair must be washed every 48 to 72 hours to avoid removing the natural oil that the scalp produces as a defense.


Protein treatments containing formaldehyde can cause skin, eye, and throat irritation

protein treatment

Formaldehydes evaporate with the heat of the flat iron and turn into toxic vapors.

When I apply these protein treatments in the salon, I use a mask and do them in a specific and ventilated area of the salon.


 When those vapors are inhaled, they produce serious irritations in the throat, nose, and eyes. 

I offer my clients a mask to protect their mouth and nose, and I also recommend that they close their eyes during the sealing process.


If the protein treatment touches your skin, you should rinse immediately with water.

Not even stylists apply the protein treatment to the scalp. We always leave two to three centimeters of growth to avoid contact of the product with the scalp and roots.



Protein treatments are excellent for nourishing and strengthening hair, but they have side effects.

To avoid unpleasant surprises, go to a professional. A stylist will evaluate your hair and recommend the most suitable protein treatment to prevent unwanted side effects.

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