Main content
The Causes of Damaged Hair & How to Fix It

The Causes of Damaged Hair
and How to Fix It

If your damaged hair is in need of repair, then you’ve come to the right place.
This simple guide will put the strength back in your strands.

No one wants damaged hair, we all aspire for shiny, supple, healthy hair. In fact, 30% of women’s main concern is damaged hair. Unfortunately, when damage sets in the easiest way to conceal the signs is with heat styling which, you guessed it, causes more damage and the vicious cycle begins. Below we explore what damaged hair looks like, what causes the damage and how to get your healthy hair back.

The Causes of Damaged Hair & How to Fix It

What does damaged hair look like?

· Dry and brittle
· Dull and lacking shine
· Little to no bounce or elasticity
· Split ends
· Tangles easily
· More porous, so hair drinks up products…
· But styling products don’t work as well
· Texture isn’t smooth
· Color may have changed


The Causes of Damaged Hair & How to Fix It

What does healthy hair have that damaged hair doesn’t?

Healthy hair is abundant in lipids that cement the hair cuticles together, ensuring a smooth strand that is impermeable, strong and shiny. Keratin is another essential component of healthy hair. It’s a protein consisting of amino acids and is responsible for the hair’s inner cohesion, creating an internal fiber backbone. Hair with the optimal level of keratin is strong and healthy.

Lastly, there are KAPS (keratin associated proteins) which are micro-proteins found in healthy hair that bond and link the keratin together. KAPS are only found in hair, virgin hair is abundant in KAPS, but disappear when hair is damaged.

What causes damaged hair?

There are three main types of damage - mechanical, chemical and external - and plenty of causes that sit in each category.

Mechanical Hair Damage

Mechanical damage is caused by friction to the hair, which can come in many forms. Harsh brushing, using heat tools too much, excessive blow-drying or styling in salons. This type of mechanical damage will be visible on the cuticle - you’ll notice dry, dull strands, a texture change and breakage.

The Causes of Damaged Hair & How to Fix It

This is what causes damaged hair and how to fix it

Chemical Hair Damage

Chemical damage is just that, damage caused by chemicals. This could be poorly applied chemicals at home like permanent color, or in-salon services that haven’t been carried out with care such as color, perming or straightening hair treatments. All chemical treatments come with the risk of some damage but, these days, much of the damage is avoidable which is why it is so important to visit a salon that you trust.

Chemical damage is visible on the cuticle, but the damage can also go deep into the cortex of the hair weakening the bonds within your strands which can lead to color and texture change, excessive hair breakage, as well as the appearance of dull, dry hair.

External Damage

Every day our hair comes into contact with pollution and UV rays, these external factors can attack our hair leading to texture and color change, as well as weakened strands that are more prone to breakage.

The Causes of Damaged Hair & How to Fix It

How do I know if I have damaged hair?

Often, you can tell if your hair is damaged because so many of the signs are highly visible. However it’s important to know how damaged your hair is. Head to any Kerastase salon and as part of the diagnosis at the start of you appointment, your hairdresser can carry out a Resistance Test. This involves taking just one strand of hair and gently stretching it.

If it stretches and returns to normal = strong resistance.

If it stretches and remains slack = lacking strength (erosion level 1-2).
If it snaps = very damaged (erosion level 3-4).


Your hairdresser will also talk to you about your current styling routine, the products you use and more to get a complete picture of what could be causing the damage and how to fix it and prevent it in future.

The Causes of Damaged Hair & How to Fix It

How can I fix my damaged hair?

Kerastase has two collections that are targeted towards repairing damaged hair - Therapiste and Force Architecte. Therapiste is a range of hair products specifically for hair lacking strength that is at the erosion level 1-2. This type of damage tends to be caused by mechanical damage, so excess friction and heat tool use.

Taking inspiration from healthy hair, the Therapiste range contains Fibra-KAP, inspired by those naturally occurring KAPS, its packed with ingredients like amino acids and wheat protein hydrolat that help to bond the keratin in the strands and keep hair strong. It also boasts Sève de Résurrection, the resurrection plant is known for its ability to survive the harshest environments and is able to come back to life even after 10 years of near death, Therapiste contains this precious resilient sap.

The Causes of Damaged Hair & How to Fix It

The range includes Soin Premier Therapiste, a nourishing and protective pre-shampoo; Bain Therapiste, a gentle renewing shampoo; Masque Therapiste, a deeply reparative hair mask; and Serum Therapiste, to reinforce the hair fiber, protect against heat and repair split ends.
Force Architecte, on the other hand, is a powerhouse range designed to repair very damaged strands that are at the erosion level 3-4. This is the hair that breaks easily, usually caused by chemical damage.

The Causes of Damaged Hair & How to Fix It

This collection also contains the resurrection plant, alongside Vita Ciment which is composed of pro-keratin, a protein that mimics the function of keratin to rebuild the hair, and Ceramid, like those all-important lipids in healthy hair, it acts like the cement to bond the keratin, strengthening the hair fiber from the inside.

This range includes Bain Force Architecte, a strengthening and repairing shampoo; Ciment Anti-Usure, an anti-breakage conditioner; Masque Force Architecte, to deeply reconstruct, detangle and strengthen the hair; and Ciment Thermique, to strengthen hair from the inside, to speed up blow-drying time to reduce further damage and to protect against the heat. Whatever damage your strands are dealing with, Kerastase has a solution that will strengthen your hair and get it back to its glossy best.

Shop The Damaged Hair Routines

Discover Related Articles

Discover how we combine our deep knowledge of hairdressers and their clients to imagine a world of hair care products that would exceed expectations

The Best Hair Growth Products For Men

Play the Parisian Kérastase Hair Challenge Game

Enjoy a moment to have fun, take time and care for yourself. Try our entertaining new Game below for your chance to win 10% off your next order.
Kerastase Chronologiste Luxury Holiday Gift Set

Hairstyle Ideas - Our Pro Stylist Advice

Any day is a good day to try out a new look. At Kérastase we want you to express your style and stand out at every party on your calendar while taking the best possible care of your hair.
How Argan Oil Became a Hair Care Hero

How Argan Hair Oil Became a Hair Care Hero

Argan hair oil uses argan oil which is a precious oil ingredient that has aided the health and beauty of skin and hair
in its native Morocco for centuries. Known as “liquid gold” for its rich color and raw power, it is a highly
beautifying and healing hair oil rich in natural nutrients. Argan oil is a miracle ingredient that we love
to use in formulations that promise incredible shine and softness, a key component in glow-giving
hair care collections like Elixir Ultime and Aura Botanica.

Find Your Nearest Salon

Far more than the place to get your root touch-up or an occasional trim, book an appointment at your nearest Kérastase salon for a complimentary personalized hair diagnosis.

Find a Salon

Services Your Personal Care

Kérastase Fusio-Dose In Salon Hair Treatment

Fusio-Dose In Salon

Learn about the signature in-salon service that transforms
hair quality in under 5 minutes.

Learn More
Kérastase Hair Quiz

The Right Products for You

Take the online hair quiz to find the best hair care
and treatment mix for your hair.

Start Now

Orientation message
For the best experience, please turn your device