Why hair falls out in autumn: Causes, how much is normal and which professional treatments work

In autumn, almost everyone notices more hair in their brush and on their pillow — and many panic. The reassuring news: some of this shedding is normal and seasonal. But how do you know what is normal and when it becomes a problem? In this guide, we explain why hair falls out more in autumn, how many strands a day are normal, what other causes may be behind it, and which professional treatments really help — plus when it is time to see a doctor. This is a care guide, not a medical one.

How Much Hair Is Normal to Lose per Day

The short answer: normally we lose 50–100 strands a day, and during periods of seasonal shedding, this number may temporarily increase. Strands fall out and grow back constantly — it is a natural cycle, not an alarm sign in itself.

The Hair Strand Growth Cycle

Each strand goes through three phases: growth (anagen, for years), transition (catagen, for a few weeks), and rest/shedding (telogen, after which the strand falls out and a new one grows). Normally, most strands are in the growth phase; in autumn, a larger proportion simultaneously enters the shedding phase.

When Shedding Becomes a Problem

It becomes a cause for concern when: it lasts more than 2–3 months, you notice visible thinning (wider part, thinner ponytail), bald patches appear, or the shedding is accompanied by itching/redness. In these cases, a specialist consultation can clarify the cause.

Why Hair Falls Out More in Autumn

Seasonal Telogen Effluvium

In autumn, more strands simultaneously enter the telogen (shedding) phase — a phenomenon called seasonal telogen effluvium. It is temporary and reversible: the strands fall out, but the follicles remain active and grow new ones. Usually, it subsides within a few weeks.

The Summer Effect: Sun, Salt, Chlorine

Summer stresses the hair and scalp: sun, salt, chlorine, dehydration. The effect is seen in autumn, when weakened hair breaks and falls out more easily. That is why autumn is also the ideal season for reconstruction — see the guide on damaged hair.

Other Common Causes

Stress and Hormonal Imbalances

Intense stress and hormonal changes (thyroid, contraceptives, menopause) can trigger or accentuate shedding. The effect often appears 2–3 months after the triggering event.

Iron, Zinc, and Vitamin D Deficiencies

Iron deficiency (common in women), zinc deficiency, or vitamin D deficiency directly affects hair health. Here, a set of tests and, if necessary, doctor-recommended supplementation do more than any cosmetic product.

Postpartum and Transitional Periods

Postpartum shedding is very common and temporary: after pregnancy, the strands that were “retained” during this time all enter the shedding phase. It usually normalizes within a few months.

Professional Treatments: What Works

Cosmetic products do not “stop” shedding caused by a medical issue, but they support the scalp, strengthen the strand, and can reduce seasonal or breakage-related shedding.

Anti-Shedding Serums and Ampoules

Scalp serums and ampoules (e.g., the Kérastase Genesis range) stimulate, support the follicle, and reduce breakage-related shedding. They are applied to the scalp as part of a routine, according to the directions. See the range in the Genesis collection and the Kérastase range.

Strengthening Shampoos — What to Look for on the Label

A strengthening shampoo gently cleanses and delivers ingredients that strengthen the fiber and support the scalp (amino acids, niacinamide, caffeine, strengthening complexes). Avoid harsh formulas that dry out the scalp.

The Complete Routine, Step by Step

Strengthening shampoo → reconstruction treatment/mask → scalp serum/ampoules → leave-in protective product. Consistency for at least a few weeks is key. See the range in professional hair treatments.

How Long Until Results Are Seen

Patience: because hair has its own cycle, the first signs (fewer fallen strands, new growth at the roots) usually appear within 6–12 weeks of consistent routine. An ampoule course should be completed, not stopped after a few days.

Mistakes That Worsen Shedding

• Tight hairstyles (ponytail, tight bun) that stress the roots.
• Excessive heat without heat protection.
• Aggressive brushing on wet hair, when the strand is most fragile.
• Drastic diets that cause deficiencies.
• Giving up the routine after a few days, before the effect appears.

When to See a Doctor

See a dermatologist or doctor if: shedding is heavy and lasts more than 2–3 months, visible thinning or bald patches appear, you have associated symptoms (fatigue, weight changes — possibly thyroid-related), or you suspect a deficiency. Cosmetic products complement, but do not replace, a medical consultation.

What Products You Need

You can find anti-shedding serums, ampoules, and strengthening shampoos in the anti-shedding collection, the Genesis range, and the rest of the Kérastase range. For reconstructing hair weakened by summer, see the professional treatments.

Conclusion

In autumn, increased hair shedding is usually normal and temporary (seasonal telogen effluvium), accentuated by summer stress. It becomes a problem when it lasts more than 2–3 months or visible thinning appears — then it should be medically investigated. In the meantime, a consistent routine with an anti-shedding serum/ampoules, strengthening shampoo, and reconstruction supports the hair, with results in 6–12 weeks. See the anti-shedding range from ProBeauty.

Frequently Asked Questions (FAQ)