A keratin treatment is one of the most searched-for hair services in the UK, and if your hair turns to frizz the moment the air gets humid, it is easy to see why. Done well, a keratin treatment can leave hair noticeably smoother, glossier and far quicker to style. But the marketing around it is confusing, so here is a clear, honest guide to what a keratin treatment actually is, the benefits, the different types, whether it damages your hair, how long it lasts, and how to care for keratin-treated hair afterwards.

What is a keratin treatment?

Keratin is the main structural protein your hair is made of. It gives each strand its strength and its smooth outer surface. Heat styling, colouring, sun and everyday wear gradually rough up the outer layer of the hair (the cuticle), which is what leaves it looking frizzy, dull and prone to flyaways.

A keratin treatment is a cosmetic smoothing service, usually done in a salon. A keratin-rich formula is applied to clean hair and sealed in with heat from a flat iron. The result is a smoother cuticle, less frizz and hair that is easier to blow-dry. It is a styling and smoothing treatment, not a medical or hair-growth product, and it does not change the hair that grows from your scalp in future.

The benefits of a keratin treatment

• Less frizz, especially in humidity the smoother cuticle resists moisture in the air, so hair stays calmer on damp days.
• Faster, easier styling many people find their blow-dry time drops noticeably because the hair is already smoother.
• More shine a flatter cuticle reflects light more evenly, so hair looks glossier.
• A more manageable feel tangles and knots are often reduced, which can mean less tugging when you brush.

Be realistic too: a keratin treatment smooths and softens the hair you already have. It will not regrow hair, stop hair loss or change your natural texture permanently, and a reputable salon will not claim otherwise.

Types of keratin treatment: Brazilian, smoothing and straightening

Not all keratin treatments are the same, and salon menus can be vague. Broadly you will come across:

• Keratin smoothing treatment the gentler option, designed to reduce frizz and add shine while keeping more of your natural movement. Results are more subtle and fade sooner.
• Brazilian keratin treatment a stronger, longer-lasting smoothing and straightening effect that tames more stubborn frizz. The term covers a range of formulas, so always ask what is being used.
• Keratin straightening treatment aimed at a sleeker, straighter finish rather than just frizz control.
• Keratin-infused home products shampoos, masks and serums containing keratin or similar conditioning proteins. They will not match a salon service but can help maintain smoothness between treatments.

Whatever the name, ask what is in the formula and request a patch test, particularly if you have a sensitive scalp or known sensitivities.

Does a keratin treatment damage your hair?

This is one of the most common questions, and the honest answer is: it depends on the formula and how it is applied. A keratin treatment itself is a smoothing service, but the high heat used to seal it in, and some of the ingredients in stronger formulas, can be tough on hair if overdone or applied carelessly. To keep hair healthy:

• Choose an experienced stylist who can match the treatment to your hair's condition.
• Avoid stacking it straight on top of heavy bleaching or other harsh chemical work without advice.
• Follow the aftercare below, since dryness and breakage are far more likely from poor maintenance than from the treatment alone.

If your hair is already fragile or very damaged, talk it through with your stylist first, and see a trichologist if you are worried about breakage or thinning.

How long does a keratin treatment last?

It varies with the type of treatment, your hair type and, above all, your aftercare. As a rough guide, a lighter smoothing treatment may last a few weeks, while a fuller Brazilian-style treatment can last a couple of months or so. The effect washes out gradually rather than stopping abruptly, so hair eases back to its natural texture over time rather than all at once.

Can you do a keratin treatment at home?

You can use keratin-infused shampoos, masks and serums at home to support smoothness, and there are at-home keratin kits available. They will not replicate a professional salon result, and the high-heat sealing step is harder to do safely yourself, so manage your expectations. For a full treatment, a trained stylist will get safer, more even results. Home products are best thought of as maintenance between salon visits rather than a true substitute.

How to care for keratin-treated hair

Aftercare is the single biggest factor in how long the smoothness lasts. A few habits make a real difference:

• Choose a gentle, sulphate-free shampoo. Harsh detergents strip the hair more aggressively and can shorten how long the smoothing lasts. A milder, sulphate-free wash is kinder to treated hair and to your scalp. Watermans haircare is sulphate-free and designed to cleanse gently, which makes it a sensible choice for maintaining a smoother style.
• Do not over-wash. Washing every single day works the treatment out faster. Stretching the time between washes helps it last.
• Use lukewarm water and a conditioner or mask. Keeping hair conditioned supports that smooth, glossy finish.
• Be gentle with heat. You will need less heat styling anyway, so take advantage and give your hair a break where you can.
• Protect it overnight. A silk or satin pillowcase reduces friction and helps keep hair smooth between washes.

Who keratin treatments suit, and who should take care

Keratin treatments tend to suit people with frizzy, coarse or hard-to-manage hair who want an easier styling routine. If your scalp is irritated, broken or very sensitive, or if you are pregnant or breastfeeding, speak to your stylist and, if in doubt, a GP or pharmacist before booking, as some formulas may not be suitable. If you notice unusual or sudden hair shedding or scalp problems, see a GP or a trichologist rather than relying on a cosmetic treatment to mask it.

Did You Know?

• Keratin is not unique to hair. The same protein forms your nails and the outer layer of your skin, which is why all three can look dull and brittle when they are not well looked after.
• Frizz is largely a humidity story. Hair is hygroscopic, meaning it draws in moisture from the air, and that swelling lifts the cuticle and creates frizz, which is exactly why smoothing treatments target the cuticle.
• Hair is roughly 90 percent keratin by dry weight, so it really is the headline ingredient of every strand.
• A silk pillowcase is not just a luxury. Less friction overnight means less mechanical roughing of the cuticle, which helps any smooth style, treated or not, last longer.

Frequently asked questions

Is a keratin treatment good for your hair?

For frizzy or hard-to-manage hair it can make styling much easier and hair look smoother and glossier. Whether it is right for you depends on your hair's condition, so an experienced stylist's assessment matters.

Does a keratin treatment damage hair?

The treatment is a smoothing service, but the heat and stronger formulas can stress hair if overdone or applied poorly. A skilled stylist and good aftercare keep that risk low.

How long does a keratin treatment last?

Roughly a few weeks for a light smoothing treatment, up to a couple of months for a fuller Brazilian-style one, depending on your hair and how you care for it.

Can I do a keratin treatment at home?

You can maintain smoothness with keratin-infused shampoos, masks and serums, but home kits will not match a salon treatment and the heat-sealing step is harder to do safely yourself.

A keratin treatment can be a brilliant way to spend less time fighting frizz and more time enjoying smoother, glossier hair. Keep your expectations realistic, look after the result with a gentle, sulphate-free routine, and you will get the most out of it.