Seasonal hair shedding is a temporary peak in hair loss, concentrated between September and November, lasting four to eight weeks. It corresponds to a synchronisation of the hair cycle: hairs that switched to the resting phase during the summer fall out together two to three months later. Three markers tell you whether your shedding belongs to this phenomenon or deserves medical advice: how long it lasts, whether the fallen hairs have a bulb, and the state of your overall density.
The hair cycle, in three phases
Losing hair is a normal, permanent process. Every hair follows a cycle independent of its neighbours.
| Phase | What happens | Duration | Share of the head of hair |
|---|---|---|---|
| Anagen | Active growth | 2 to 6 years | 85 to 90% |
| Catagen | Transition, the follicle winds down | A few weeks | 1 to 2% |
| Telogen | Rest, then shedding as the next hair pushes through | 2 to 3 months | 10 to 15% |
The mathematical consequence: losing between 50 and 100 hairs a day is physiological. The key point lies elsewhere: every hair that falls at the end of its cycle is normally replaced by a new one, in the same follicle. Shedding only becomes a problem if the replacement does not follow, which is not the case in seasonal shedding.
Why autumn?
Several studies have observed a seasonal variation in the proportion of hairs in the telogen phase, peaking at the end of summer. The dominant scenario is this: during the summer, an unusual number of hairs switch to the resting phase, more or less at the same time. As that phase lasts two to three months, the hairs programmed in July and August fall together in September and October.
Aggravating factors often add to it: UV that oxidised the scalp and the fibre over the summer, a subject covered in our article on post-summer repair, back-to-work stress, and changes of rhythm.
Normal shedding or shedding to watch: the 3 markers
- Duration. Seasonal shedding spreads over four to eight weeks. Beyond three months of clearly increased shedding, the calendar is no longer the culprit.
- The nature of the fallen hair. A hair at the end of its cycle falls whole, with a small white swelling at the base, the bulb. Hairs snapped clean off, with no bulb, are breakage rather than shedding: the issue is then the fibre, covered in the 10 signs of damaged hair.
- Overall density. Seasonal shedding creates neither thinning patches nor a lasting widening of the parting.
See a doctor or a dermatologist if the shedding lasts more than three months, if it creates patches or bald areas, if it comes with other symptoms (unusual fatigue, menstrual changes, weight fluctuations), or if it follows a specific event such as childbirth, a shock or an illness. Non-seasonal hair loss has identifiable causes, iron deficiency, thyroid issues, post-partum, intense stress, and responds very well to treatment once diagnosed.
What to do during the period
The aim is not to stop a natural phenomenon, but to give the new hairs the best possible start. While the old ones fall, the next generation is already growing.
- Look after your scalp. Regular, gentle washes, a two to three minute fingertip massage at every shampoo, a lukewarm then cool rinse. The toning actives in the /RESET Shampoo, caffeine and rosemary oil, support a favourable follicular environment: their real effects and their limits are set out in our article on caffeine.
- Reduce mechanical stress. Loose hairstyles, gentle brushing, no tight hair ties. No point adding breakage to shedding.
- Look after the general picture. Sleep, a diet supplying protein, iron and zinc, stress management. Food supplements can support, never replace a diagnosis if the shedding falls outside the markers above.
What happens next
Every hair shed at the end of its cycle already has its successor on the way in the same follicle. The short little hairs appearing around the hairline and the parting in the following weeks are precisely that regrowth: it is a sign of good health, not of breakage.
Then allow a few months for those new hairs to gain length and give your hair back its usual visual density. Use the period to strengthen your existing lengths with the 4-step routine, and note what you observe from one year to the next: knowing your own seasonal rhythm changes how you experience October a great deal.
Seasonal shedding: the essentials
- A 4 to 8 week peak between September and November, linked to the hair cycle.
- 50 to 100 hairs a day is the norm outside the peak.
- Hair with a white bulb = normal shedding. Hair snapped clean off = a fibre problem.
- No shampoo stops seasonal shedding: those hairs were programmed to fall.
- More than three months, patches or other symptoms: see a doctor.
Frequently asked questions about seasonal shedding
How many hairs is it normal to lose per day?
Between 50 and 100 in normal times, and appreciably more during the seasonal peak. It is the duration and the presence of the bulb that separate normal from concerning, not the exact count.
How long does seasonal shedding last?
Generally four to eight weeks, between September and November. Clearly increased shedding lasting more than three months warrants a consultation.
Are men and women equally affected?
Yes. The phenomenon is simply more noticeable on long hair, where fallen hairs are more visible, and in people whose density is already fine.
Can a shampoo stop seasonal shedding?
No, and be wary of anyone who promises it: the hairs falling out were programmed to fall weeks ago. A gentle shampoo with toning actives supports the scalp and regrowth, which is not the same promise.
Does washing your hair make more of it fall out?
No. Washing releases hairs that were already at the end of their cycle and would have fallen anyway. Spacing shampoos out does not reduce shedding, it simply concentrates the fallen hairs into fewer washes.
When should you see a doctor?
If the shedding lasts more than three months, creates thinning areas or patches, comes with other symptoms, or follows childbirth, a shock or an illness. A medical assessment identifies the cause and allows appropriate treatment.
Sources
- Randall V. A., Ebling F. J. G., "Seasonal changes in human hair growth", British Journal of Dermatology, 1991.
- Kunz M., Seifert B., Trüeb R. M., "Seasonality of hair shedding in healthy women complaining of hair loss", Dermatology, 2009.
Article written by the KERA NEXT editorial team from the studies cited. It does not constitute medical advice and is not a substitute for a consultation.