Does washing your hair often make it fall out?

You rinse, run your fingers through your hair, and they come out with a strand caught between them. In the plughole, a small dark clump. So you decide the water, the lather and the rubbing are pulling it out, and you start washing less often to spare it. It’s a very common reflex, and it rests on a mistake.

Why you see so much in the shower

The French Society of Dermatology (SFD) is clear: contrary to popular belief, shampoo doesn’t make hair loss worse¹. It only reveals shedding that happens anyway.

Hair grows in cycles. At any time, about 15% of your follicles (the small pockets hairs grow from) are resting. The hair stays there for two to four months without growing, then a new hair grows underneath and pushes the old one out². That hair is hanging by a thread. Shampoo, a scalp massage, a comb: anything that touches it makes it fall.

That’s why shedding is most noticeable after washing or brushing, in the plughole or on the hairbrush². The rest of the time, hairs fall on the pillow, in the sink, on your clothes, and you don’t see them. In the shower they all land in the same place, and it’s the sight of them together that’s frightening.

How many hairs per wash is normal

People often say it’s normal to lose 50 to 100 hairs a day. The British Association of Dermatologists gives a wider range, 30 to 150². But how many go during the shampoo itself?

A team of dermatologists in Beijing put the question to 176 adults. Each washed their hair once a day, three days running, over a filter cloth that caught every hair that fell. The hairs were then counted one by one³.

Among the 71 people with no hair problem, the average was 27.9 hairs per wash, with no difference between men and women³. The authors point out that this is far fewer than the 100 hairs a day often quoted: many fall elsewhere, through the day³. These are averages, with big differences from one person to the next, and the study only covers Chinese adults recruited in hospital.

Your hair length matters too. DermNet, the New Zealand dermatologists’ website, notes that people with long, thick hair notice shed hairs more than those with fine or short hair⁴. Ten 40 cm hairs make quite a tangle.

Washing less: the optical illusion

When you wash less often, the hairs that are ready to fall don’t stay attached. They come loose but stay caught in the rest of your hair until the next wash. Then they all go at once.

Dermatologists actually use this. In a test developed in Italy, the patient is asked not to wash their hair for 5 days, then to count every hair that falls during the wash⁵. The Beijing team compared their figures with those from this method: after 5 days without shampoo, about 71 hairs were collected in people with pattern hair loss, against 52 with daily washing³. In people going through temporary shedding, about 248 against 126³. These figures come from different studies and patients, but the authors put the gap down to the 5-day wait³.

So washing less saves no hair. It bunches the hairs together, which makes each wash more alarming and can feed the fear. Even doctors have to factor this in: a test where they gently tug on a lock of hair to see how many come out can look falsely normal if you’ve washed your hair in the previous 48 hours².

How often should you wash your hair?

There’s no single rule. The SFD advises washing your hair whenever it needs it¹. The American Academy of Dermatology (AAD) is more specific: wash your hair based on how often it gets dirty or oily. With straight hair and an oily scalp, you may want to shampoo every day. With dry, textured, curly or thick hair, wash it when needed, at least once every 2 to 3 weeks⁶.

A study in China looked at the real habits of 1,500 people aged 18 to 75⁷. The more often they washed their hair, the less dandruff they had and the happier they were: fewer than 3 “great hair days” a week when washing twice or less, more than 5 when washing every day⁷. Perceived hair loss and brittleness even improved slightly with more frequent washing⁷.

Limits to bear in mind: several authors work for a major shampoo maker, the participants had fairly straight hair, and hair loss wasn’t counted, only self-reported⁷. The authors themselves say they don’t know whether their results apply to very curly hair⁷.

Is a clean scalp better?

For the scalp, yes. In the second part of the same study, 60 people who usually washed their hair twice a week or less went a week without shampoo, then four weeks shampooing every day. Daily washing reduced sebum, flakes, odour and oxidised oils, which irritate the skin⁷. And it didn’t lower the oils that protect the inside of the hair, the argument most often made against frequent washing⁷.

The AAD advises applying shampoo to your scalp rather than the lengths: you clean where the oil builds up without drying out the ends⁶. It also notes that flakes can come from not shampooing often enough⁶. If you have dandruff, your choice of shampoo matters more.

One last, purely visual benefit: clean hair has more volume, which hides thinner areas from view¹.

What really damages hair

Shampoo isn’t the problem, but some habits around it can make hairs snap, which then gets mistaken for hair loss. The AAD recommends detangling wet hair with a wide-tooth comb rather than a brush, not rubbing it hard with a towel, and limiting heat from hairdryers and straighteners⁶. The SFD adds that colouring and relaxing applied to the roots can weaken hair, and advises avoiding them or spacing them out¹. We cover these habits in 4 gentle habits for hairdryers and straighteners.

When shedding in the shower needs a check

The amount is only one clue. Shedding that starts suddenly, with far more hair than usual coming from all over the scalp, looks like temporary shedding, often triggered a few months earlier by childbirth, a high fever or major stress². It usually settles on its own, but if it lasts more than 6 months it’s called chronic², and a blood test can look for low iron or a thyroid problem².

Another, subtler clue: small, very fine hairs among the others. In the Beijing study, they were far more common in people with pattern hair loss, and the authors advise a check-up if you find several in the plughole³. Either way, a doctor can take stock and offer you a treatment if needed.

Judge by photos, not by the plughole

Counting the hairs at the bottom of the shower is a poor guide: the number changes with the day, the time since your last wash, your hair length. What counts is what stays on your head.

Take the same photo every week instead, hair dry, styled the same way, in the same light and always on the same day relative to your wash. Aim at your parting, crown and temples. If you change how often you wash, within a few months you’ll see whether your density moves, instead of trusting the day’s clump.

Calvap helps you do exactly that: your previous photo appears as a see-through overlay so you line up in the same spot, the journal keeps the date you changed your routine, and your photos stay on your phone.