Five things to check first

These checks lean on the British Association of Dermatologists (BAD) leaflet on telogen effluvium, "a condition where more hair than usual falls out from your scalp", because the Liège study below found more telogen effluvium between July and October. The Primary Care Dermatology Society (PCDS) hair loss pathway for GPs asks questions you can answer at home. Your answers are not a diagnosis.

Roots or snapped pieces

PCDS asks: "Is the hair loss from the roots, or is the hair breaking?" A hair that came out with its root has shed; a piece that snapped part-way along is breakage. A root does not make the amount normal, since hairs lost in telogen effluvium come out from the root too: how many, from where and for how long is what counts. If most are snapped pieces and you have no bald or scaly patches, that is breakage: our suggestion is to handle your hair gently.

Where it is thinning

• All over, with less volume: in telogen effluvium, BAD says "You may notice a decrease in hair thickness and loss of hair volume rather than patches."
• Thinner on top or a wider parting: in female pattern hair loss, BAD says there is "diffuse thinning of the hair, mainly over the top of the scalp, the mid part line becomes more visible and widened".
• Smooth bald patches: BAD says this is how alopecia areata typically starts.
• Thinning at the temples: in women, NICE Clinical Knowledge Summaries (CKS) says it "may indicate traction, frontal fibrosing alopecia, or hypothyroidism" (traction: hair loss from styles that pull); in men, PCDS says pattern hair loss thins hair "over the temples and crown".

Your scalp

• Looks normal: BAD says telogen effluvium usually has no other symptoms, though occasionally the scalp feels tender or different.
• White flakes and itch: how the NHS describes dandruff (see Dandruff and seborrhoeic dermatitis).
• Scaly, sometimes sore patches with patchy hair loss or itch: symptoms of a fungal scalp infection (scalp ringworm), which NHS Inform says is "most common in children".
• Inflamed, or with pus-filled spots or scarring: NICE CKS says these may suggest scarring alopecia, and NHS Inform links pus-filled sores to more severe fungal scalp infection. Go promptly if you see pus, a large inflamed sore or scarring (our suggestion; see When to stop waiting). If your scalp got sore, red or spotty soon after a tight style went in, loosen or change the style now too (our suggestion; see Traction alopecia).

The last six months

Telogen effluvium follows a trigger by two to six months in UK sources. BAD's common triggers include childbirth; severe trauma or illness (especially if a high fever occurs); stressful or major life events; surgical procedures; marked weight loss and extreme dieting; severe skin problems affecting the scalp; starting new medications; and stopping a hormone treatment (such as coming off the contraceptive pill).

NHS Inform adds nutritional deficiencies like iron deficiency and endocrine disorders like under or over active thyroid, and for 1 in 3 people diagnosed, BAD says, no cause can be found. If a new medicine fits the timing, our suggestion is to raise it with whoever prescribed it rather than stop taking it.

How long, how fast and how often

PCDS also asks how fast the loss is and whether it has happened before. BAD says telogen effluvium typically starts suddenly, is called chronic after more than 6 months and "can reoccur if the possible underlying cause such as iron deficiency is not treated".

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When to stop waiting

Our suggestion: book a GP rather than wait if you notice:

• bald patches
• a wider parting, a receding hairline or thinning at the temples or crown
• scaly patches with hair loss, or a red or swollen scalp
• shedding with other symptoms, such as tiredness (see Iron deficiency and thyroid problems)

Go promptly (our suggestion) for pus-filled spots or sores, a large inflamed sore, or a scalp that looks scarred: PCDS says scarring alopecia needs "an urgent referral", since "once scarred the alopecia is irreversible", and NICE CKS advises urgent referral for a suspected kerion, which NHS Inform calls "a large inflamed sore" that "can ooze pus". If your scalp got sore, red or spotty soon after a tight style went in, loosen or change the style now too (our suggestion; see Traction alopecia).

Even without these signs, book a GP if shedding is still heavy by December, trigger or not, or lasts more than 6 months, when BAD calls telogen effluvium chronic (our suggestion). You need none of these to see a GP: the NHS says go if you are worried. More on each sign: When it is not a seasonal shed and Who to see.

What seasonal shedding studies found, August to February

None of the NHS, NHS Inform, BAD, PCDS or NICE CKS hair loss pages we checked mentions seasonal shedding. The 6 to 8 week figure on brand pages traces to no study we could find, even where a page credits it to BAD.

Studies give group averages, not your timetable. The only UK study of seasonal hair loss we could find followed 14 men with indoor jobs in Sheffield for 18 months (published 1991); the study of women below comes from a Zurich clinic (823 women) whose patients were already worried about hair loss.

Autumn hair loss has no settled cause: Liège's authors call ultraviolet light's influence "possible". BAD says a follicle that stops growing "rests for two to four months and then a new hair begins to grow. The new growing hair pushes out the old hair, causing it to shed." Our reading: the Zurich women's summer peak in resting hairs would show as later shedding.

August and September

These studies found more hair falling out in late summer: start your photos now (our suggestion, see Keep a record). In the Sheffield men, shed hairs "reached a peak around August/September", at about 60 a day, "more than double that during the preceding winter".

October and November

October is the last month named for a rise in the study summaries we could read: if you are shedding heavily now, check for a trigger and the stop signs (our suggestion). In Liège, Belgium, hair samples from 2,857 people complaining of increased hair loss showed telogen effluvium more often "between July and October".

December

Heavy shedding now is not what the seasonal studies describe, since none puts its main peak in winter. After a trigger such as childbirth it may still be telogen effluvium, but our suggestion is to book a GP rather than wait: BAD says "A blood test may be carried out to exclude other possible causes of hair loss."

January and February

These studies found less hair falling out in winter, so the December advice still applies; a shed starting now fits a trigger in the last six months better than the season (our reading). No study summary we could read describes a rise in February: in the Zurich women, the share of resting hairs was lowest "towards the beginning of February", says a 2016 editorial by one of that study's authors.

While you wait

Keep a record

Our suggestion: photograph your parting, hairline and temples (hair pulled back) and crown every two weeks, in the same place and light. If a later photo shows a wider parting, a receding hairline, or thinner temples or crown, book a GP then, whatever the month. If you count shed hairs, count on wash days with the same gap between washes, and compare only with your own counts: UK sources disagree on a normal daily figure, and a wash-day count is not a daily count.

Handle your hair gently

BAD's self-care advice for telogen effluvium starts with these four points:

• Avoid harsh brushing or combing of hair.
• Limit the use of heated hair tools such as hairdryers, straighteners, or curlers
• Avoid hair bleaching/relaxing techniques or any treatment that uses harsh chemicals
• Limit use of tight hairstyles.

Our guide to protecting hair from heat damage covers using hot tools less often and at lower heat; it is about protecting the hair you have, not about shedding.

Skip the shedding fixes

The NHS page on women and hair loss says: "Do not be taken in by claims for wonder products."

• Biotin. The MHRA, the UK medicines regulator, says in its May 2025 safety roundup: "Biotin may interfere with thyroid immunoassays and the risk of interference increases with higher doses of biotin." Our suggestion: if you take biotin or a hair, skin and nails supplement (check the label), tell whoever arranges your blood test before the sample is taken.
• Rosemary oil. We could not find a trial in shedding.
• Scalp massage or a hair loss shampoo. We could not find a study of either in seasonal shedding.

Minoxidil is for pattern hair loss

Regaine foam's UK product information says it is for pattern hair loss ("alopecia androgenetica") and "Topical minoxidil is not indicated when there is no family history of hair loss, hair loss is sudden and/or patchy, hair loss is due to childbirth, or the reason for hair loss is unknown." The NHS women's hair loss page says "A proven treatment for female-pattern baldness is a hair lotion containing minoxidil", and "Always contact a GP or dermatologist for advice before starting or finishing any treatments or medicine for alopecia." If you use Regaine foam, its leaflets say "Temporary hair loss may occur during the first 2-6 weeks of use", that "it should stop within a couple of weeks" and "If this hair loss continues for longer than 2 weeks, stop using the product and talk to your doctor."

Covering visible scalp

BAD says visible scalp "can happen in very severe cases of telogen effluvium" and lists options to discuss with your doctor, including "Using camouflaging hair fibre powder or spray (the fibres stick to existing hair)" and "Using a volumizing shampoo". A root colour spray is temporary colour, not fibres: our L'Oréal Magic Retouch review covers using one over thinner spots and notes scalp trouble in six of the 100 buyer reviews it read, including an allergic reaction, so patch test first. Our suggestion: take each photo on dry hair after a wash and before you spray, check your scalp first, and never spray a sore, scaly or broken one.

When it is not a seasonal shed

Shedding after a trigger (telogen effluvium)

Our reading of the figures below: it usually settles by itself, and BAD calls it chronic after more than 6 months.

UK sources differ on how long it lasts. BAD says the shedding phase "lasts between 3 to 6 months". PCDS says complete regrowth comes "within three to six months" unless the trigger is repeated, while its pathway says it "typically resolves 6-9 months after triggering event", counting from the trigger.

Pattern hair loss

NICE CKS says the onset of female pattern hair loss "may be at any age following puberty", and BAD says male pattern hair loss "can affect men of any age", usually as "a receding frontal hairline and loss of hair from the top of the head". The NHS says both are permanent and usually run in the family.

The NHS says "Finasteride and minoxidil are the main treatments for male pattern baldness" and "Minoxidil can also be used to treat female pattern baldness. Women should not use finasteride." These treatments "do not work for everyone" and "only work for as long as they're used". If this sounds like you, see a GP (our suggestion).

Alopecia areata

BAD says it causes sudden hair loss, typically starting with bald, smooth patches that "are not inflamed or scaly", and short, tapered "exclamation mark hairs" may be seen at the edge.

Traction alopecia

Caused by styles that pull, it often affects the hair margins but can occur anywhere on the scalp, says PCDS, and is reversible if the style is changed early. A St George's University Hospitals NHS leaflet says "Pain, redness, dimpling of the scalp and small pus filled lumps (pustules) soon after installing a particular hairstyle are early signs", and warns it "can lead to scarring, causing permanent hair loss in later stages". Our suggestion: loosen or change a style that pulls now, and go promptly for pus (see When to stop waiting).

Scalp ringworm

The NHS ringworm page says: "Speak to a pharmacist first if you think you have ringworm." Its GP advice, in full (the second point covers the scalp):

Non-urgent advice: See a GP if:

• ringworm has not improved after using antifungal medicine recommended by a pharmacist
• you have ringworm on your scalp - you'll usually need prescription antifungal tablets and shampoo
• you have a weakened immune system - for example, from chemotherapy, steroids or diabetes

Dandruff and seborrhoeic dermatitis

The NHS dandruff page says to use an anti-dandruff shampoo "for up to 4 weeks to see if your dandruff gets better", and its symptom table gives "Tinea capitis, known as ringworm" as a possible cause of a "Red or silver rash on scalp, sometimes with patchy hair loss" (see Scalp ringworm). NICE CKS says seborrhoeic dermatitis "may be associated with or may aggravate hair loss". The NHS GP advice, in full:

Non-urgent advice: See a GP if:

• you still have dandruff symptoms after using anti-dandruff shampoo for at least 4 weeks
• your dandruff is bad or your scalp is very itchy
• your scalp is red or swollen
• you have flaky, itchy patches on your face or other parts of your body

Iron deficiency and thyroid problems

The NHS lists hair loss among less common symptoms of iron deficiency anaemia ("you notice more hair coming out when brushing or washing it"), whose symptoms also include "tiredness and lack of energy" and "paler than usual skin", and among common symptoms of an underactive thyroid, which also include "feeling extremely tired (fatigue)" and "feeling cold more than usual". It says see a GP if you think you might have either. NHS Inform lists patchy hair loss among signs of an overactive thyroid and says: "See your GP if you are experiencing any of these symptoms."

Who to see

The NHS hair loss page says:

Non-urgent advice: See a GP if:

• you're worried about your hair loss

It also says: "See a GP to get an idea about what's causing your hair loss before thinking about going to a commercial hair clinic." NHS Inform, for Scotland, says:

Contact your GP practice if:

• you're worried about abnormal, unexpected or sudden hair loss

You should speak to your GP practice if you're worried about hair loss. They'll normally ask about your hair loss and examine your hair to help find out the cause. Sometimes you may need a blood test.

BAD says: "If hair shedding does not get better, then it is recommended that you see your doctor to rule out other causes of hair loss." None of the three sets a number of weeks to wait. For support, the NHS points to Alopecia UK, which runs local and online support groups.

Frequently asked questions

How many hairs a day is normal to lose?

UK sources give different figures for normal daily hair loss. The NHS says "We can lose between 50 and 100 hairs a day, often without noticing", NHS Inform says up to 100, and BAD says most people lose "between 30 and 150 hairs from their scalp every day". All three include 100 a day; your own counts over time tell you more (our suggestion).

Does washing or brushing make shedding worse?

No source we checked shows that washing makes you lose more hair, though BAD says increased shedding is "most noticeable after washing or brushing". NICE CKS, on pattern hair loss, says hair "may be shampooed as frequently as desired without fear of worsening hair loss". BAD advises avoiding harsh brushing or combing.

Will my hair grow back?

Shed hair is normally replaced: BAD says "New hairs grow to replace the ones that fall out, and the total number of hairs on the scalp usually stays the same." Telogen effluvium "usually gets completely better without any treatment", BAD adds, though volume can take many months to return. The NHS says male and female pattern baldness are permanent, and a St George's NHS leaflet says traction alopecia "can be reversed with care" but "can lead to scarring, causing permanent hair loss in later stages".

Does seasonal hair shedding happen every year?

The longest study we could find that followed the same people, ten men over 8 to 14 years, found a yearly cycle: on average, the share of resting hairs peaked at the end of summer and beginning of autumn. Men with very few resting hairs showed no cycle and some had roughly two peaks a year; we could not find a similar study in women. A shed every autumn does not prove it is seasonal, since BAD says telogen effluvium "can reoccur if the possible underlying cause such as iron deficiency is not treated".

Should I take biotin or hair vitamins?

We could not find a trial showing that any supplement shortens a seasonal shed. The NHS says a varied and balanced diet should give you all the biotin you need, and "Taking 0.9mg or less a day of biotin in supplements is unlikely to cause any harm". BAD suggests considering supplements if your diet is restricted, for example vegan or vegetarian. The MHRA warns biotin may interfere with thyroid blood tests, more so at higher doses, so tell whoever arranges a blood test that you take it, before blood is taken (our suggestion).

Related reading

• How to protect hair from heat damage: a UK guide
• Root touch up spray for grey hair UK: L'Oréal Magic Retouch review