Hair Loss
A symptom with several causes — and one of them is a clock
What it is
Hair loss is not one condition. It is a symptom produced by several distinct processes that look superficially similar in the mirror and are completely different underneath. The most important division is between NON-SCARRING hair loss — where the follicle survives and regrowth remains possible — and SCARRING hair loss, where inflammation destroys the follicle and replaces it with scar tissue, and the loss is permanent. Beneath that division sit the common patterns: androgenetic (pattern) hair loss, telogen effluvium, and alopecia areata. Working out which one is happening is the entire task, and it is not something that can be done from a photograph or a hair count. It is done by looking at the scalp.
Why it matters
Because the treatments are different, and because one of these has a deadline. Pattern hair loss is gradual and treatable, and nothing is lost by taking a few weeks to decide what to do. Telogen effluvium is temporary and usually reverses on its own once the trigger has passed. Alopecia areata is autoimmune, unpredictable, and now has genuinely effective drug treatment. But SCARRING alopecia destroys follicles permanently, and hair lost that way cannot be recovered by any treatment that exists — so the months spent on a supplement are months of follicles that are not coming back. Hair loss is also, frequently, the visible edge of something systemic: iron deficiency (which itself has a cause that needs finding), thyroid disease, PCOS, or autoimmune disease. Treating it as an appearance problem means missing all of that.
What BioSignal knows about treating this
What works for Hair Loss
BioSignal’s clinical summary, most important first.
- IDENTIFY WHICH KIND IT IS — pattern, telogen effluvium, alopecia areata, or scarring. These look alike and are treated completely differently, and one of them is permanent if it is not caught. Nothing else on this list is worth doing before this
- SEE A DERMATOLOGIST URGENTLY IF THE SCALP ITCHES, BURNS, HURTS, IS RED OR SCALY, OR HAS GONE SMOOTH AND SHINY — these are the signs of scarring alopecia, in which follicles are being destroyed permanently and early treatment is the only thing that preserves them
- Look for and correct the reversible causes — iron deficiency, thyroid disease, PCOS, medication effects. Low ferritin is worth finding here for two reasons: it contributes to the hair loss, and it has a cause of its own that needs identifying
- For pattern hair loss, topical minoxidil — the best-evidenced non-prescription treatment, effective in both men and women, and it must be continued: stopping reverses the gain
- For pattern hair loss in men, oral finasteride or dutasteride (5-alpha-reductase inhibitors) — strong randomized evidence for halting progression and partial regrowth; a clinician's prescription, with side effects worth discussing honestly
- For pattern hair loss in women, anti-androgen therapy such as spironolactone, and low-dose oral minoxidil — clinician-directed, and effective
- For alopecia areata, intralesional corticosteroids and, in extensive disease, JAK inhibitors — a genuinely transformative recent advance and a specialist decision
- For telogen effluvium, TIME and removal of the trigger — it is self-limiting and usually recovers within 6–9 months once the cause has passed. Nothing needs to be bought
- Hair transplantation for stable pattern loss, once medical therapy has been optimised
Signal Records relevant to this condition
Interventions and contributing factors — some of these records describe a cause rather than a cure. The rating shown is BioSignal’s confidence in that Signal Record, not a claim about how well it treats this condition. Open any of them for the full evidence.
- CreatineHigh confidence
The best-evidenced supplement in sports science for strength, power and lean mass — and one of the cheapest. The kidney fear is a misread lab value. The broader claims (cognition, disease) are a long way behind the performance evidence.
- ZincHigh confidence
Strong evidence where there is deficiency or a specific indication. No benefit in replete people — including for testosterone — and excess causes copper deficiency.
- Vitamin DHigh confidence
Effective for deficiency and for bone health in at-risk groups. For broad disease prevention in adults who are already replete, the largest trials are null — and confidence in that null is high. Routine testing of healthy adults is not supported.
- CollagenModerate confidence
Real but modest evidence for skin hydration and elasticity, heavily shadowed by industry funding. Not established for joints, bone, tendon, hair or nails. It is an incomplete protein and does not build muscle. For skin, a retinoid and sunscreen have far better evidence and cost far less.
- Testosterone TherapyModerate confidence
Effective for genuine hypogonadism; no established benefit at normal levels. Suppresses fertility. Ask why testosterone is low before treating the number.
- Menopausal Hormone TherapyHigh confidence
The most effective treatment for menopausal symptoms. For most women under 60, benefits outweigh risks — and the risks have been overstated for two decades.
New to this? Read these first
How this usually unfolds
- Recognize risk factors
- Get diagnosed
- Track key biomarkers
- Lifestyle first
- Evidence-based treatment
- Long-term monitoring
Who is at risk
- Family history — the dominant factor in androgenetic (pattern) hair loss, in both sexes
- Age — pattern hair loss affects the majority of men and a large minority of women over a lifetime
- Iron deficiency, with or without anaemia (low ferritin)
- Thyroid disease — BOTH underactive and overactive
- PCOS and other causes of androgen excess in women
- Menopause — falling oestrogen unmasks androgenic effects on the scalp
- Autoimmune disease — alopecia areata clusters with thyroid disease, vitiligo, coeliac and type 1 diabetes
- A major physiological shock 2–4 months earlier: childbirth, surgery, severe illness, high fever, crash dieting, significant weight loss
- Medications: chemotherapy, retinoids, anticoagulants, some antidepressants, beta-blockers, and changes to hormonal contraception
- Testosterone therapy — accelerates pattern hair loss in those genetically predisposed
- Tight hairstyles, extensions and traction over years (traction alopecia — preventable, and permanent once established)
How it's diagnosed
Hair loss is diagnosed by examining the SCALP, not by counting hairs. The single most consequential question is whether the follicular openings — the tiny pores hairs emerge from — are still present. If they are, the follicle survives and regrowth is possible. If the scalp is smooth and shiny and those openings have vanished, the process is scarring, and that is a dermatological urgency rather than a cosmetic concern. Beyond that, the pattern tells the story: gradual thinning at the temples and crown suggests androgenetic; diffuse shedding all over, starting 2–4 months after a shock, suggests telogen effluvium; discrete, sharply defined round patches suggest alopecia areata. A small number of blood tests then look for the reversible systemic causes.
Key biomarkers
Lifestyle
Explore this condition across BioSignal
Related Foundations
Related Signal Records
Frequently asked questions
Why is my hair falling out?
There is no single answer, and the honest response is that the question cannot be settled from the amount of hair you are seeing. The four common processes are: pattern (androgenetic) hair loss, which is gradual, genetic, and follows a recognisable pattern; telogen effluvium, a diffuse shed that begins 2–4 months after a shock such as childbirth, illness, surgery or a crash diet, and which recovers on its own; alopecia areata, an autoimmune condition producing discrete round bald patches; and scarring alopecia, which is uncommon, permanent, and urgent. Overlying all of these, iron deficiency and thyroid disease are common reversible contributors that are worth testing for. Which one you have is determined by looking at your scalp, and it changes what you should do next completely.
Does biotin work for hair loss?
No — not unless you are biotin deficient, which is rare, and there is something about biotin far more important than whether it works. HIGH-DOSE BIOTIN INTERFERES WITH COMMON LABORATORY BLOOD TESTS. It can make troponin — the test used to diagnose a heart attack — read FALSELY LOW, and the FDA has issued safety communications about this after a death associated with a missed diagnosis. It also distorts thyroid function tests in a way that can mimic Graves' disease and lead people to be treated for a disease they do not have. Most 'hair, skin and nails' supplements contain biotin at doses hundreds of times higher than any dietary requirement. So the risk here is not that you waste your money. It is that a supplement taken for a benefit it does not provide can cause a real heart attack to be missed in an emergency department. If you take biotin, stop it several days before any blood test and tell the clinician you have been taking it.
Does creatine cause hair loss?
Not established — and BioSignal will not overstate this in either direction. The claim traces back to a single small 2009 study of 20 rugby players, which found a rise in DHT, a hormone involved in pattern hair loss. That study did not measure hair loss, and no study since has shown creatine causing hair to be lost. So the honest position is narrow: one small trial found a hormonal change, the outcome has never been demonstrated, and the claim has been repeated for fifteen years as if it were settled. It is not settled — but nor has creatine been proven safe for the hair of someone strongly predisposed to pattern baldness, because the study that would show that has not been done. BioSignal's Creatine record carries the full evidence.
Does iron deficiency cause hair loss?
It is a real and reversible contributor, and it is one of the few things genuinely worth testing for. Low ferritin is associated with telogen effluvium and appears to worsen pattern hair loss, and correcting a demonstrated deficiency can improve shedding. Two important caveats. First, the evidence for correcting iron in people whose ferritin is NORMAL is not there — this is a reason to test, not a reason to supplement blindly. Second, and more important: iron deficiency in an adult always has a cause. Finding low iron is the beginning of the investigation, not the end of it, and in men and postmenopausal women it is a reason to look at the gastrointestinal tract.
What actually works for pattern hair loss?
Topical minoxidil has the best evidence of anything available without a prescription, works in both men and women, and must be continued indefinitely — the benefit reverses if you stop. For men, oral finasteride and dutasteride have strong randomized evidence for halting progression and producing partial regrowth; they are prescription drugs with side effects that deserve an honest conversation with a clinician. For women, anti-androgen therapy such as spironolactone and low-dose oral minoxidil are effective and clinician-directed. Hair transplantation is a real option once medical therapy is optimised and the loss is stable. Notice what is not on this list: no supplement, gummy, shampoo, or 'DHT-blocking' serum has evidence approaching any of these.
When should hair loss send me to a doctor urgently?
If your scalp itches, burns, feels tender or painful, or is red, scaly or inflamed. If the skin where hair has been lost looks smooth and shiny and you can no longer see the small openings the hairs came out of. If hair is lost in sudden, sharply defined patches. If it comes with other symptoms — weight change, fatigue, irregular periods, new acne or facial hair. And if hair is being lost rapidly. The reason for urgency is scarring alopecia: an inflammatory process that destroys follicles permanently, in which early treatment is the only thing that preserves what is left. It is uncommon, it is frequently missed, and it is the one form of hair loss where waiting has an irreversible cost.
My hair started falling out three months after having a baby / being ill. Is that normal?
Yes — that is telogen effluvium, and the delay is the diagnostic clue. A physiological shock pushes a large share of hair follicles into their resting phase all at once; they then shed together, two to four months later, which is why the hair loss appears long after the event that caused it and can feel inexplicable. It is diffuse rather than patterned, it is temporary, and it typically recovers within six to nine months once the trigger has passed. It is worth checking ferritin and thyroid function, because those can prolong it. Beyond that, nothing needs to be bought, and there is no supplement that speeds it up.
Evidence summary
The evidence here is unusually clear about what works, and it is almost entirely absent for what is sold. Topical minoxidil and oral 5-alpha-reductase inhibitors (finasteride, dutasteride) have strong randomized evidence in androgenetic alopecia, with finasteride halting progression in the large majority of treated men; benefit reverses on discontinuation for both. JAK inhibitors have transformed the treatment of severe alopecia areata and are supported by phase 3 trials. Telogen effluvium is self-limiting and resolves with removal of the trigger. Iron deficiency is a genuine reversible contributor, and correcting a DEMONSTRATED deficiency helps — while supplementing iron in the iron-replete does not, and carries harm. For biotin, the position is not merely that evidence of benefit in non-deficient people is absent: high-dose biotin is a documented cause of clinically significant laboratory interference, including falsely low troponin, and carries an FDA safety communication. For creatine, the hair-loss claim rests on a single small study reporting a DHT increase, with no study demonstrating the outcome; BioSignal grades it not established and declines to assert it in either direction. And scarring alopecias cause irreversible follicular destruction, which is why the only genuinely time-critical statement on this page is a referral, not a treatment.
References & sources
- American Academy of Dermatology — guidelines of care for androgenetic alopecia
- British Association of Dermatologists — guidelines for the management of alopecia areata
- FDA Safety Communication — biotin interference with laboratory tests (troponin and other immunoassays)
- Randomized controlled trials of topical minoxidil and oral finasteride in androgenetic alopecia
- Phase 3 trials of JAK inhibitors (baricitinib, ritlecitinib) in severe alopecia areata
- Cochrane and systematic reviews of interventions for alopecia areata
Educational information — not medical advice
Is this condition page clear, accurate, and useful? Your feedback shapes what we review next.
Give feedback