Disclaimer: This content is for informational purposes only and does not constitute medical advice, diagnosis, or professional treatment. Always consult a healthcare provider for scalp/hair conditions and perform a patch test before using any chemical products.
Your hair cuticle tells pretty much everything about the health of your hair. It can make or break your hair.
But what is it, and why does it play such an important role in the health of your hair? First, some myth-busters, hair follicle, and hair cuticle are not interchangeable terms.
What is Hair Cuticle?
The hair cuticle is made up of protein-based, flat hair cells overlapping like the shingles on a roof or the scales on a fish. Because the cuticle is on the surface, it’s the protective layer of the hair shaft.
It’s affected by environmental factors (sun, humidity, water, pollution) and hair products containing harsh chemicals.
Because it is the protective layer, the hair cuticle’s state indicates your hair’s state, in general.
When you move your fingers from top to bottom over a single strand of hair, you’ll notice that it’s smooth. But when you move your fingers from the end of the shaft toward the root, you’ll probably notice that it’s “bumpier.”
It might even make a squeaky sound when dry as your fingers pass over it. That’s because your fingers are moving in the direction of the flattened hair cells of the cuticle layer.
Function
The cuticle is the gateway to the cortex, allowing compounds and chemicals into the inner part of the hair shaft.
Depending on what substance is applied to the cuticle, it will open or close, and the cortex will be nourished and moisturized (or damaged). The cortex is the layer that indicates the natural color, curls, texture, and thickness of the hair itself.
If you suffer from split ends, the protective cuticle has been worn away, and the inner cortex is beginning to fray like the ends of a thread. This condition usually arises when your hair has been treated harshly, from brushing too hard or exposure to chemicals.
Types of Hair Cuticles
Your hair’s ability to absorb and retain moisture is determined by the structure of your hair cuticle. Low-porosity cuticles absorb less moisture but retain it for longer, while high-porosity cuticles absorb moisture quickly but also release it sooner.
Low-porosity hair is often considered healthy, while high-porosity hair is considered damaged. However, more porosity doesn’t always indicate a damaged cuticle; it can be genetic.
For example, 3C, 4B, and 4C hair types are naturally more porous than straighter hair because the cuticle scales slightly lift at the natural bends of the curls. These types of hair are inherently more prone to damage.
Heat styling, chemical treatments, and harsh environmental exposure can alter your hair’s porosity by physically breaking down the protective layer.
If your hair cuticle has missing scales or wider, lifted gaps than what is natural for your hair type, it is considered a damaged cuticle.
Hair Follicle vs. Hair Cuticle
You will see the term hair follicle being used for hair cuticles and vice versa, but they aren’t nearly the same thing. Every hair on your body grows out from a sac-like area at the bottom of your skin’s pores.
That hole is known as a hair follicle, and it is there that a unique cluster of hair reproduction cells is located. Hair follicles are where your hair is formed and sprouts from.
The cuticle, however, is part of the anatomy of an actual hair strand. No matter the texture or length of an individual hair, all hair consists of three layers: the outermost cuticle, the inner cortex, and, in some cases, the medulla below the cortex.
What is a Healthy Hair Cuticle?
Cuticle is the gateway to the cortex, allowing compounds and chemicals into the inner part of the hair shaft. A healthy hair cuticle is intact. It guards the hair from being over-moisturized or dried out.
Depending on what substance is applied to the cuticle, it can open slightly to admit them or close, and the cortex will be nourished and moisturized.
Generally, the hair cuticle will open slightly for alkaline substances, like hair conditioners, and close for acidic substances, like apple cider vinegar rinses.
Highly alkaline substances like hair bleach, relaxers, baking soda, and many shampoos open the cuticle so wide that the layers can break or disintegrate. Highly acidic substances, like lemon juice and white vinegar, can break down the hair cuticle. So it’s best to look for products that are pH-balanced.
What is a Damaged Hair Cuticle?
A damaged hair cuticle has missing or lifted scales. This could be genetic or caused by brushing, heat, chemical processing, sun exposure, etc.
A damaged hair cuticle means that anything you put on your hair will reach the cortex, which might not be a good thing.
For instance, while pure water has a neutral pH of 7, it is actually higher than hair’s natural acidic pH (4.5-5.5). If your hair gets overloaded with water, it causes the cortex to swell and knock off more cuticle shingles.
High Porosity Hair
High porosity hair has gaps in the cuticle. This can be genetic (common in curly hair) or caused by damage from excessive heat styling or chemical processing.
The gap or open cuticles allow high porosity hair strands to absorb moisture or color pigments quickly. Those raised cuticles also release the moisture or color pigments faster. So the hair becomes very dry, or the color fades sooner.
Low Porosity Hair
Low porosity hair is the healthy cousin of high porosity hair. It has a hair cuticle with fewer gaps and densely compacted cell layers. This can make it more challenging to moisturize and hydrate. This is usually a genetically occurring condition where the cuticle layers are very tightly packed.
How to Open Low Porosity Hair Cuticles
If you have low porosity hair, the cuticle shingles are laid flat and tight. Whether you are trying to deep condition or deposit hair color, you must use heat, water, or pH to open up the cuticle so products can penetrate.
Alkaline products open the hair cuticle. Most clarifying shampoos are alkaline and also remove product buildup from hair. So wash your hair with a clarifying shampoo (max once or twice a month) to raise your cuticle.
Heat is the most effective way to open low-porosity hair. Wash with warm water to gently swell the hair shaft before toning treatment. For deep conditioning, use a steamer, heated gel cap, or hot towel. This sustained heat forces the cuticle to stay open while the treatment penetrates.
Permanent hair color contains ammonia. Ammonia is alkaline, so you do not need extra heat for these.
Medium Porosity Hair
You could say this hair type is the ideal one. It easily absorbs hydration and retains moisture. But that’s because the cuticle shingles are already partially open.
If they are opened further, they might lose their grip on the hair. Learn more about the differences between high and low porosity hair.
Why Does the Hair Cuticle Get Damaged?
Hair cuticles are the protective outer layers of the hair shaft. Cuticles get damaged when this outer layer is lifted, cracked, or worn away by chemicals, heat, friction, and the environment.
Common causes for hair cuticle damage include:
- Chemical processing: Permanent color, perms, and relaxers use alkaline products that swell hair and lift the cuticle so the chemicals can reach deeper layers.
- Heat styling: High heat can dry and crack the cuticle. Extreme heat on damp hair can also form bubbles inside the hair shaft, making it weak and brittle.
- Maintenance: Rough towel drying, brushing wet hair, and tight styles can rub the cuticle scales out of place, so the protective outer layer becomes lifted and rough.
- Sun Exposure: Hair cuticle is made of keratin proteins. The UVA and UVB radiation from the sun breaks down the proteins and weaken cuticle.
How to Repair Damaged Hair Cuticle
The hair cuticle is made of dead tissue, so it cannot heal or grow back like skin.
What you can do is improve damaged cuticles by smoothing and sealing the surface. Some treatments coat the hair and fill rough areas, so it feels softer, looks shinier, and breaks less.
The best repair options include:
- Bond repair treatments: Strengthen the inside of the hair and reduce breakage, especially after bleach or color. It mainly works inside the hair (cortex), not on the cuticle itself. But it still helps damaged cuticles indirectly because stronger hair breaks less.
- Protein and keratin treatments: Add temporary strength and support to weakened hair and help the cuticle surface feel smoother.
- Sealing products (serums, oils, silicones): Create a protective layer that lowers friction and tangling.
If the cuticle damage is severe, the only permanent solution is trimming the damaged hair. Until then, gentle care can help slow further damage while you grow your hair longer.
Follow these tips to avoid more cuticle damage:
- Detangling your hair wet or dry depends on your hair structure. Wet hair is more elastic and prone to snapping. If you have straight hair, let it air dry first. If you have curly or textured hair, always detangle when wet and coated with conditioner using a wide-tooth comb or flexible brush.
- After shampooing, use a deep conditioner and apply a moisturizing leave-in conditioner or frizz-reducing cream or gel.
- Avoid using heat tools like blow-dryers, curling irons, and flat irons.
- If you must blow-dry, keep the dryer moving constantly and hold it about 6 inches from the hair to prevent concentrated heat damage.
- Wear your hair in a natural style that can be air-dried instead of blow-dried.
- Don’t bleach, chemically straighten, or perm your hair.
- Don’t permanently color your hair; instead, use a temporary wash-out rinse.
- Avoid rubbing your hair vigorously with a towel. This action causes friction and can upset the hair’s cuticle.
- Eat healthy foods that support hair growth and increase hair strength.
- Get your hair trimmed regularly.
- Use high-protein treatment masks that are rich, creamy, and emollient at least once a week.
- Use products with heavier natural oils and butter, such as coconut oil, argan oil, and shea butter.
- Wash your hair with cool or lukewarm water.
- Rinse your hair once a week with a water-diluted apple cider vinegar solution to help lower pH. The ratio of vinegar and water should be 1:10 (e.g., 2 tsp apple cider with a standard 1 cup of water). DO NOT apply undiluted vinegar. It is too acidic and will burn your scalp.
Damaged hair cuticles are the primary reason your locks become dry and unmanageable because when they’re open, the cortex is more susceptible to moisture loss and breakage.
Strengthen your damaged lock by reducing the external factors that caused damage to your hair, and also remember to eat a healthy diet.
FAQs
Alkaline substances (like ammonia or clarifying shampoos) cause the cuticle to swell and open. Additionally, very curly hair structures naturally have slightly lifted cuticles on the outside bend of the curl.
No, hair cuticles do not grow back or repair themselves. Because hair is dead tissue, a fresh, healthy cuticle only appears with new hair growth from the scalp.
You can perform a simple water test. Drop a clean, product-free strand of hair into a glass of water. If it sinks immediately, the cuticles are highly porous (likely lifted or damaged) and are absorbing water quickly. If it floats for a long time, the cuticle is tightly packed and healthy (low porosity).
Hair cuticles do not close by themselves over time. You must apply a pH-balanced or slightly acidic product (like a diluted apple cider vinegar rinse or a proper conditioner) to lower the hair’s pH and smooth the scales back down after an alkaline process.
On average, six to ten layers of cuticle shingles make up the hair cuticle. Fine hair has a lower number of layers, and coarse hair has a higher number of layers.
Each cuticle scale is made of three microscopic sublayers: Epicuticle (the protective outer membrane), Exocuticle, and Endocuticle.
Under a microscope, a damaged cuticle looks frayed and uneven, with lifted, chipped, or broken scales that expose the inner cortex, similar to a fraying piece of rope.
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