We're going to discuss hair-washing frequency, what was learned from some clinical trials with people doing different hair-wash frequencies, and why they got the results that were reported. Also: How you can apply this research to your life?
But first: Storytime!
I told the dermatologist I often wash my hair almost every day, often with dandruff shampoo. There was an awkward pause.
It felt like I gave the wrong answer. My scalp, my rules! But, is there a right answer? How are we measuring this?
We can turn to clinical trials for some clues. Where people wash their hair at different frequencies and different assessments are made, data are collected. From individual reports to image-scanning to measuring oils in hair and breakage or hair-fall.
Some recent studies might surprise you: Scalp health and scalp comfort were better with near-daily or daily washing. Breakage was reduced for some people, and hair fall decreased.
- In a 2021 study, groups of people were asked to wash their straight-to-wavy hair either daily, or only once per week. Both their scalp-health and hair-health was better with daily washing. That means dullness, dryness, frizz, breakage were improved. And scalp-health improved in terms of itch, irritation, flaking, dryness, and odor. They measured similar oil-content in the inside of daily-washed and once-weekly washed hair. *Here I have a quibble, because unless you use a gentle shampoo and in small amounts, you will likely have less oils in the hair. And for some hair types, oils are more easily removed from the interior of hair, like Type 4 hair.
- Another study published in 2026 of people with a greater diversity of hair-types than the one above, (curly hair included), which also kept track of whether people had an oily or dry scalp. The researchers found that people who shampooed daily lost fewer hairs per day, and experienced less breakage than with less-frequent shampooing (once-weekly, or twice to three times weekly). The downside? Having curly or quite long hair negated the breakage benefit.
- A 2026 study of women with inflammatory/autoimmune hair loss (frontal fibrosing alopecia), found that less-frequent washing and more-frequent leave-on product use, correlated with higher rates of frontal fibrosing alopecia. This is a correlation, not proof of a cause. Does the frequent washing to remove products and sebum reduce disease occurrence? Is it the leave-on products themselves? As yet, that is unclear. But it's a result that warrants investigation.
All this points to more-frequent washing being helpful for both skin and hair.
Why, why why? What is going on here? When we've been told that it's better to wash hair infrequently?
Why might people be losing less hair with frequent washing?
I checked, because I knew you'd wonder, this was calculated as "hairs lost per day," not "hairs lost per wash-day."
Oils on the skin oxidize into irritants like oleic acid. Dead skin cells and oils accumulate around the roots of hair in a sticky film with oils and possibly sweat that traps yeasts and bacteria and their metabolites. The result can be itching and irritation. If you don't remove the offending substances, you can end up with low-grade inflammation and greater incidence of more obnoxious skin issues like Seborrheic dermatitis if you're a sensitive person or have allergies.
We lose less hair when our scalps are not under oxidative stress from products and accumulated oils. In 2026, the most common way to remove that residue is shampooing. So that's what they studied.
Why less breakage with more frequent washing (except for long or curly hair)?
Wow. Counterintuitive, right? Hair that gets re-hydrated by washing and has oily residues removed tends to be more manageable. Hydration = flexibility and reduced breakage.
Natural oils get a little 😇 halo of benevolence because they're all natural! But skin oils can also be sticky or greasy or tacky (waxy) and dulling. Cosmetically, for shine, for root volume, and for tangles, accumulated scalp-oils in your hair can be a problem. Regarding breakage, if we're getting oils to the ends of our hair, there might be less breakage with grooming designed to distribute oils. But things don't always go according to plan. And breakage is not just about oils (lubrication). It also involves hydration.
Long hair has more-fragile ends that are more susceptible to mechanical damage, so any manipulation, including washing, increases the chance of breakage. Curly and/oror Type 4 hair has such a talent 🌟 for tangling, and kinking hair often has some mechanical-damage-prone, vulnerable areas along the strand. So these hair-types may experience more mechanical damage from more-frequent washing that negates the anti-breakage benefits.
How often should YOU wash your hair? How to use this information.
1) Scalp comfort: Top priority. You can't have the healthiest, most manageable hair with an uncomfortable scalp. Irritation and inflammation will eventually take their toll on your follicles. Seriously. An irritated scalp is often very slow to "forget" the irritation. Wash as often as you need to for scalp comfort. Don't force yourself to wait too long.
- If your hair and scalp tolerate frequent washing: Go for it. No apologies. If this dries your hair out, keep in mind that with frequent washing you can (and possibly should) use conditioner or leave-in products with extra moisture (humectants, proteins) and/or oils, depending on your hair and the product. Frequent washing doesn't mean that your hair has to be able to handle it without any help from products!
- If you can only wash your hair once per week because of the risk of breakage, or a longer styling or drying-time, pay attention to the signals you get from your scalp and give it what it needs. Just because you can't wash, doesn't mean you can't do some scalp-care.
- There are some products on this page in the "Leave-on" section (towards the bottom of the page) with scalp-health benefits that can keep your scalp comfortable and thriving between washes. Many of those are anti-oxidant, or promote a harmonious skin microbiome. There are products that can truly help your skin between washes, it's not all marketing. Find the right product and you'll be a lot more comfortable between washes.
- Washing 2-3 times per week? Awesome! Read the section about hair treatments below ↓to keep your hair in great condition.
- Need to change your wash-frequency in summer or winter or when you're doing certain activities? Scalp care comes first! Do what you gotta do.
2) Use of treatments for frequent shampooers: Hair treatments should make washing less stressful to your hair. Keep your hair healthy by using treatments more frequently. Oil pre-wash treatments, bond-repair, deep conditioning, protein treatments.
What does "more frequently" mean?
- If somebody who washes their hair once per week uses a deep conditioner or protein treatment or bond-repair treatment once a month, that's once per 4 wash-days.
- If you're washing your hair 3 times per week, you'd need to use that product every 2 weeks to approach the same frequency based on a per-wash timing.
- If you're washing your hair daily, you'd need to use it once per week. Though that could be a bit too much.
- This is not a hard-and-fast rule, it's just something to think about.
Is it damaging to wash hair infrequently? I was told it was better...
It's not bad to wash your hair once per week if your hair needs that frequency. Going for 2 weeks is likely to cause some minor flaking and itch, even in healthy scalps. We need to remove oils and exfoliate the skin, shampooing is a way of doing that to get the clean, fresh-feeling hair that's mainstream.
Infrequent washing might be a problem if it's causing stress for your scalp in the form of itching or discomfort or flaking or tension. Infrequent washing can make hair more difficult to detangle rather than easier to detangle, because of the accumulated sebum and dehydration.
I don't mean to imply, "Science says you should your hair frequently!" No guilt, no pressure.
The clinical testing found that, in a short-term trial, people did better with more frequent washing. They didn't have the ability to compare the vast diversity of scalps and hair types and hair-care strategies, and climates that are out there. These trials pointed to reasons why more-frequent washing isn't as bad as it's sometimes made out to be. Sometimes more-frequent shampooing solves problems we don't expect it to solve.
And it creates some new ones, so we have to choose our products according not only to our hair, but also to our wash-frequency.
References
Punyani S, Tosti A, Hordinsky M, Yeomans D, Schwartz J. The Impact of Shampoo Wash Frequency on Scalp and Hair Conditions. Skin Appendage Disord. 2021 Apr;7(3):183-193. doi: 10.1159/000512786. Epub 2021 Feb 15. PMID: 34055906; PMCID: PMC8138261.
Rubaian NB, Alnakhli F, Albelowi LM, Alharbi A, Alnajjar D, AlHuraish DS. The Relationship Between the Frequency of Hair Shampooing and the Condition of Hair and Scalp Among the Population of Saudi Arabia. Dermatol Res Pract. 2026 May 24;2026:3472173. doi: 10.1155/drp/3472173. PMID: 42199383; PMCID: PMC13199680.
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