Washing hair in cold or warm water – what does science say?

Washing hair in cold or warm water? Lots of people ask, and the answer isn’t as simple as it seems. The internet is full of conflicting advice: some say cold water adds shine and seals the cuticle, others warn it won’t remove sebum and oil. Who’s right? Here’s what science says about water temperature – and a practical step-by-step guide to washing your hair.

Cold or warm water?

Short answer: neither icy cold nor very hot. The optimum is lukewarm water (about 35–38°C) for shampooing and cool or cold water for the final rinse. This combines the advantages of both: warm water removes sebum and dirt, while a cold final rinse closes the cuticle, adding shine and reducing frizz.

Washing hair in cold water – the effects

Pros:

• Closes the cuticle – hair is covered with overlapping scales (the cuticle); cold water makes them lie flat, visually smoothing the hair, adding shine and reducing frizz.
• Less protein loss – with a closed cuticle, less keratin escapes during washing, especially from coloured or chemically treated hair.
• Good for an oily scalp – cold water tightens pores and may gently reduce excess sebum.
• Freshness and circulation – a cold rinse stimulates microcirculation and feels refreshing.

Cons:

• Doesn’t remove sebum properly – the biggest problem: fat is much harder to remove at low temperatures, so hair can look washed but still be weighed down by oil, especially with an oily scalp.
• Discomfort, especially in winter – icy water is simply unpleasant for many people.
• Shampoo lathers less – surfactants work less effectively in cold water, so you need more product.

Washing hair in warm water – the effects

Warm water is the standard in most salons and bathrooms.

Pros:

• Removes sebum and dirt effectively – warmth breaks down fats, so shampoo works properly and the scalp gets truly clean.
• Opens the cuticle – conditioner penetrates better – ideal for conditioners and masks.
• Shampoo works better – it lathers well and cleans thoroughly.
• Comfort – especially during long detangling or mask sessions.

Cons:

• Dries hair and scalp – water that’s too hot (over 42–45°C) strips natural lipids and opens the cuticle so much that hair loses moisture too fast: dry, breaking ends and an irritated scalp.
• Colour fades – hot water speeds up the fading of dye; every wash in water that’s too hot shortens the life of your colour.
• Scalp irritation – with a sensitive or atopic scalp, hot water can worsen itching.
• Frizz – an open cuticle without a cool final rinse means frizzy, hard-to-style hair.

Is washing in cold water harmful?

Cold water doesn’t damage hair directly. The main risk is incomplete cleansing – if shampoo doesn’t work properly, a layer of sebum remains on the scalp, which over time can clog follicles and lead to dandruff or faster greasiness. This applies especially to people with an oily scalp. With a dry or normal scalp, cool water throughout is less of a problem, though still less effective than lukewarm for shampooing.

Does cold water make hair grow faster? Myth or fact?

One of the most common hair myths. Cold water doesn’t speed up hair growth in any proven way: growth happens in the follicle, deep beneath the skin, and the water temperature doesn’t biologically affect the growth cycle. Where does the myth come from? Cold water stimulates scalp circulation, and better blood supply does support follicles – but the effect is marginal and there’s no research showing measurably faster growth. If growth is your goal, a healthy diet, no iron or biotin deficiency and minimal mechanical damage matter far more.

The optimal water temperature

Stage	Temperature	Effect	When
Wetting and shampooing	35–38°C (lukewarm)	Opens the cuticle, removes sebum and dirt, shampoo lathers well	Always – the basis of effective washing
Conditioner or mask	35–38°C (lukewarm)	An open cuticle takes in nourishing ingredients	Always after shampoo
Final rinse	15–20°C (cool to cold)	Closes the cuticle, adds shine, reduces frizz	Always at the end, especially for coloured and frizzy hair
Dry scalp	33–35°C (slightly warm)	Minimises lipid loss, doesn’t irritate	Sensitive scalp, atopy, psoriasis
Oily scalp	37–40°C (warm)	Removes sebum effectively	Greasy hair – but avoid hot water with a sensitive scalp
Coloured hair	33–36°C + cold rinse	Slows down colour fading	After colouring and every day with coloured hair
Very dry or chemically treated hair	33–35°C + cold rinse	Protects the structure, closes the cuticle	Chemically damaged or worn-out hair

Tip: never wash your hair in water above 42°C. Hairdressers and trichologists agree that “scalding” the scalp is one of the most common mistakes, leading to dryness and irritation.

How to wash your hair – step by step

1. Comb before washing – dry hair detangles more easily, so you avoid tearing wet strands.
2. Wet thoroughly – lukewarm water (35–37°C) for at least 30–60 seconds.
3. Apply shampoo to the scalp, not the ends – the ends get cleaned as you rinse. Use fingertips, not nails.
4. Massage for 1–2 minutes – activates the cleansing ingredients and improves circulation.
5. Rinse thoroughly with lukewarm water – shampoo residue causes dandruff and irritation.
6. Apply conditioner to lengths and ends – skip the scalp if it gets oily. Leave for 2–5 minutes.
7. Rinse the conditioner with cool or cold water – key for shine and smoothness.
8. Gently towel-dry – don’t rub, squeeze the water out from top to bottom; rough terry towels can damage the cuticle.

When is it worth visiting a salon?

Washing at home is perfectly enough day to day if you use the right temperature and products. But now and then it’s worth seeing a hairdresser not just for a cut, but also for advice on scalp problems (dandruff, excessive greasiness), choosing the right shampoo and conditioner, or a professional wash with a scalp massage. At Haircut Express you can drop in without an appointment – find your nearest salon (38 salons in Poland) and check the prices.

FAQ

Does washing hair in cold water damage it?

Cold water doesn’t directly damage the hair structure. The main risk is that the scalp isn’t cleaned thoroughly – shampoo works less well at low temperatures, which can lead to sebum build-up. For people with an oily scalp, washing only in cold water can make greasiness worse.

What water temperature should I wash my hair in?

The optimal routine is lukewarm water (35–38°C) for shampooing and conditioning, and cool or cold water (15–20°C) for the final rinse. Warm water removes sebum effectively; cold water closes the cuticle, adding shine and reducing frizz.

Does cold water make hair grow faster?

No – it’s a myth. Cold water has no proven effect on the rate of hair growth, which is controlled by the biology of the follicle, not the temperature of the water. Cold water may stimulate scalp circulation, but the effect on growth is marginal and unproven.

Does warm water damage hair?

Lukewarm water (up to 38–40°C) doesn’t damage hair – it actually helps wash it properly. The problem is very hot water (over 42°C): it strips the scalp’s natural lipids, speeds up colour fading and opens the cuticle too much, leading to dryness and breakage.

What’s the best water temperature for washing hair?

For most people, 35–38°C (lukewarm, close to body temperature) for shampooing, and cool water (15–20°C) for the final rinse. Exception: people with a sensitive or atopic scalp should wash in slightly cooler water (33–35°C).

Does washing in cold water affect the scalp?

Yes – cold water tightens pores and may gently regulate sebum, good news for an oily scalp. But with a dry or sensitive scalp, very cold water can constrict blood vessels and hinder proper moisture. The best compromise: a cool final rinse rather than washing entirely in cold water.

Summary – what to remember

• Shampoo with lukewarm water (35–38°C).
• Final rinse with cool or cold water.
• Never hot (over 42°C) – it strips lipids, fades colour and irritates the scalp.
• Cold water doesn’t speed up growth – it’s a myth.
• Cold water doesn’t remove sebum well – a risk with an oily scalp.

Read also

• High-porosity hair – how to care for it?
• Hair oiling – which oil and how?
• Greasy hair in men – causes and solutions
• How often should you get a haircut?