Hair loss in autumn: why it happens, and what makes it normal

Journal · Hair & seasons

Hair loss in autumn: why it happens, and what makes it normal

In September and October, many people notice more hair on the pillow, in the brush or at the bottom of the shower. It is not just an impression: science has measured it. Here is what happens, what remains normal, and what deserves medical advice.

By Alexis Brousse, founder of Biologyst · Published on 2 October 2026 · Studies checked on PubMed

Autumn hair loss worries people every year, yet it most often follows a natural rhythm. At Biologyst, we prefer to explain it rather than exploit it: understand the hair cycle, learn to recognise what is out of the ordinary, then support what can be supported with nutrients whose role is recognised.

Why do we lose more hair in autumn?

Each hair follows a three-stage cycle: a long growth phase (anagen, two to six years), a short transition phase (catagen, a few weeks), then a resting phase (telogen, about three months) at the end of which it falls out to make way for a new hair. At any given time, the vast majority of hairs are growing and a small proportion are resting.

What changes with the seasons is the proportion of hairs that enter the resting phase at the same time. And because the resting phase lasts about three months, hairs that stop growing in summer fall out... in autumn.

An earlier scientific study, by Courtois and colleagues, which followed ten men for 8 to 14 years, had already described a peak of resting hairs at the end of summer and the beginning of autumn, linked to hours of sunshine.

The hairs that fall out in October often stopped growing in July.

How many hairs do we lose a day?

The figure of 50 to 100 hairs a day is often quoted. It is an order of magnitude, not a norm: it varies with density, length and how often you wash your hair. On hair-washing days you see more, simply because the hairs that were ready to fall all come out at once. What matters is the change compared with what is usual for you, and how long it lasts.

Seasonal shedding or something else: how can you tell?

• Seasonal: it appears at the end of summer or in autumn, affects the whole scalp, and fades on its own within a few weeks.
• To have checked: shedding that lasts more than three months, thinning or bald patches, itching, redness or scaly patches.
• Also worth mentioning: shedding that follows a pregnancy, rapid weight loss, a period of intense fatigue, a new treatment or major stress.

Which nutrients matter for hair?

A hair is made of almost 90% keratin, a protein rich in sulphur amino acids such as cysteine. Making it constantly draws on the follicle, one of the fastest-renewing structures in the body. A varied diet with enough protein remains the foundation.

Zinc and selenium, two nutrients to remember

Let us be precise: no nutrient has an authorised claim on hair loss, and Hair & Nail Regenesis does not promise to stop hair loss. Several nutrients do, however, carry a claim recognised in Europe for hair, including zinc and selenium: zinc contributes to the maintenance of normal hair, and selenium contributes to the maintenance of normal hair. Both also contribute to the maintenance of normal nails. Zinc is found in seafood, meat and seeds, selenium in fish, eggs and Brazil nuts.

Cynatine® HNS keratin: what research has studied

Cynatine® HNS is a hydrolysed keratin, sourced from New Zealand sheep’s wool and made soluble so that it can be consumed. It is one of the few hair ingredients to have been the subject of a published scientific study, at a precise dose: 500 mg a day.

Our ritual combining Hair & Nail Regenesis, Lactoferrine Active+ and Omega Active+.

What to do during the season?

• Detangle gently, from the ends to the roots, with a wide-toothed comb.
• Limit tight hairstyles and heat from styling tools.
• Choose a mild shampoo and rinse well.
• Eat enough protein at every meal.
• Be patient: hair grows about one centimetre a month, and the cycle is measured in months, not days.

Should you combine several formulas?

For a more complete approach, our three-formula ritual combines Hair & Nail Regenesis with Lactoferrine Active+ and Omega Active+. In this combination, it is zinc and selenium that carry the hair claim. The ritual is priced at €102.90.

To learn more about the hair cycle, also read Hair loss and brittle nails: understanding the hair cycle.

Frequently asked questions

Why do we lose more hair in autumn?

Because a larger proportion of hairs enter the resting phase during the summer. This phase lasts about three months, after which these hairs fall out, hence more visible shedding in September and October.

How long does autumn hair loss last?

Usually a few weeks. If the shedding lasts more than three months, leaves thinning patches or comes with other signs, see your doctor or a dermatologist.

How many hairs is it normal to lose a day?

A figure of 50 to 100 hairs a day is often quoted, but it is an order of magnitude that varies with density, length and how often you wash your hair. The most useful benchmark is the change compared with what is usual for you.

Which nutrients for hair?

Zinc and selenium contribute to the maintenance of normal hair. A varied diet with enough protein remains the foundation.

What does the study on Cynatine® HNS keratin say?

In a scientific study published in 2014 (Beer et al.), 48 women analysed took 500 mg of Cynatine® HNS a day for 90 days: measured hair shedding fell by 46.6% compared with the start of the study. Hair & Nail Regenesis provides 500 mg of Cynatine® HNS per 3 capsules.

How do you take Hair & Nail Regenesis?

3 capsules a day with a large glass of water, preferably in the morning or spread over the day. The 60-capsule jar lasts 20 days. Do not exceed the recommended daily dose.

Further reading

• Hair & Nail Regenesis: the product page
• The Hair & Nail ritual, lactoferrin and omega-3
• Hair loss and brittle nails: understanding the hair cycle
• Hair loss: understand before you act
• Vitamin D: from October to March, the sun is no longer enough
• ChatGPT and food supplements: how good is AI advice?