First: the reassuring arithmetic
The scalp carries around 100,000 hairs, and each lives its own cycle — growing for years, resting for months, falling. Up to about 100 hairs a day is a perfectly normal changing of the guard, and seasonal waves (autumn especially) are well described and temporary.
That is why my first question in the consulting room is never 'how many hairs fall' but 'what changed' — because the worrying thing is not shedding itself, but a change in it.
Telogen effluvium: the most common and most reversible cause
Two to three months after major stress, a febrile illness, surgery, childbirth or a crash diet, hair follicles collectively 'decide' to rest — and hair falls in handfuls. It sounds dramatic, it looks dramatic — and in the vast majority of cases it is fully reversible.
The catch is precisely the delay: shedding starts months after the trigger, so the connection is often missed. A diary looking backwards in time is half the diagnosis.
When hair loss deserves an examination
Patchy loss — smooth, round hairless areas. A visibly widening parting or a thinner ponytail in women. A receding line at the temples. Shedding combined with fatigue, weight changes, brittle nails or pallor. Itching, redness or flaking of the scalp.
Each of these is a reason not for panic but for diagnostics — behind them may sit iron deficiency, thyroid dysfunction, an autoimmune condition or androgenetic alopecia, and each is treated differently.
Why I never start with a shampoo
A shampoo sits on the scalp for minutes and cannot fix what the blood test shows. So the order in my consulting room is: history, examination of scalp and hair shaft, laboratory tests when needed. Only then treatment.
The good news: once the cause is found, hair loss is one of the most rewarding conditions to treat. The bad news: results are measured in months, not weeks — hair simply grows slowly. That is why we photograph at the start and compare objectively.
One sentence to take home
If you see more hairs on the brush this autumn — breathe: it is most likely seasonal. If you see patches, persistent thinning, or an irritated scalp — come in. Five minutes of dermatoscopy on the scalp says more than fifty internet articles, this one included.