Hair Loss Algorithm · Reasoning GP

Done

Safety

Red Flags — Identify Scarring Alopecia & Systemic Disease

Scarring (cicatricial) alopecia causes irreversible follicle destruction — do not miss these. Also screen for underlying systemic causes.

Scarring alopecia (cicatricial) Shiny atrophic scalp, absent follicular ostia on dermoscopy, progressive, irreversible. Any suspected scarring alopecia → Urgent dermatology (within 2 weeks)

Scalp malignancy Ulcerated scalp lesion, rapidly growing nodule, firm attached scalp lump, bleeding ulcer, known lymphoma → 2WW skin cancer

Tinea capitis with kerion Boggy painful scalp swelling, pustules, cervical lymphadenopathy, systemic illness (especially child) → Same-day treatment — systemic antifungal urgently

Secondary syphilis "Moth-eaten" patchy scalp and beard hair loss + systemic symptoms (rash, lymphadenopathy, oral ulcers) → Same-day STI clinic / GUM referral

Systemic lupus erythematosus Diffuse hair loss + malar rash, oral ulcers, arthralgia, serositis, photosensitivity → Urgent ANA/dsDNA, refer rheumatology

Malignancy-associated (telogen effluvium) Rapid diffuse hair loss + weight loss, fatigue, night sweats, lymphadenopathy, known cancer history → Urgent investigation for underlying malignancy

Severe nutritional deficiency Brittle hair + very low BMI (<17.5), amenorrhoea, lanugo hair, marked muscle wasting → Assess for eating disorder — urgent medical review if unstable

Trichotillomania in children Irregular areas of hair loss, short broken hairs of different lengths, scalp normal, behavioural distress → Safeguarding consideration + CAMHS referral

Scarring alopecia represents a dermatological emergency — once follicles are destroyed, hair loss is permanent and irreversible. Early treatment of lichen planopilaris, discoid lupus, or folliculitis decalvans can arrest progression. A delay of 6–12 months before referral can result in extensive irreversible baldness. Tinea capitis with kerion requires systemic antifungal therapy (terbinafine or griseofulvin) — topical antifungals do not penetrate the hair shaft and are ineffective. Secondary syphilis is a readily treatable STI that is frequently missed when presenting as hair loss.

Done

Diagnose

History — Pattern, Timeline & Triggers

The pattern and timeline of hair loss — combined with age, sex, and systemic symptoms — will identify the diagnosis in 70–80% of cases.

Pattern of loss

Diffuse (all over scalp) → telogen effluvium, AGA (F), hypothyroid. Patchy → alopecia areata, tinea capitis. Frontotemporal recession + vertex → male AGA. Frontal + crown parting → female AGA. Diffuse + receding hairline → FPHL.

Onset & timeline

Acute (<6 months) → telogen effluvium (trigger 2–3 months prior), alopecia areata. Chronic gradual → AGA, FPHL. Chronic scarring pattern → LPP, discoid lupus (ask about progression).

Trigger history

3 months prior: major illness, surgery, high fever, COVID-19, childbirth, major psychological stress, extreme weight loss → telogen effluvium (hair sheds 8–12 weeks post-trigger).

Systemic symptoms

Fatigue, weight change, cold intolerance, constipation → hypothyroid. Irregular periods, weight gain, hirsutism → PCOS. Fatigue, pallor, brittle nails → iron deficiency anaemia.

Medication history

Chemotherapy, anticoagulants (warfarin, heparin), retinoids, antithyroid drugs, lithium, beta-blockers, anticonvulsants, oral contraceptive pills (especially progesterone-dominant) — all cause hair loss.

Family history

AGA/FPHL: strong familial component (polygenic). Alopecia areata: 20% have first-degree relative with AA. Autoimmune thyroid disease.

Hair care practices

Chemical relaxers, bleaching, permanent waving → traction alopecia. Heat styling, tight ponytails/braids → traction alopecia (frontal recession). Trichodynia (scalp pain) → inflammatory alopecia.

Psychological impact

Hair loss causes significant psychological distress — routinely screen with PHQ-9 and ask about social impact. 40% of female alopecia patients develop anxiety or depression.

The 8–12 week lag between telogen effluvium trigger and shedding is the single most important piece of history in alopecia assessment — patients presenting with diffuse hair loss should always be asked about events 2–3 months prior. Failure to elicit this history leads to unnecessary investigation and incorrect diagnoses. AGA affects 50% of men by age 50 and is significantly under-recognised in women (FPHL affects 40% of women by age 70 with the Ludwig classification).

Done

Diagnose

Classification — Scarring vs Non-Scarring, Diffuse vs Patchy

The scarring vs non-scarring distinction is the critical first branch — it determines urgency and treatability.

Androgenetic alopecia (AGA/FPHL)

Male: Hamilton-Norwood pattern (frontotemporal recession, vertex). Female: Ludwig pattern (diffuse vertex, preserved frontal hairline). Commonest alopecia. DHT-mediated follicle miniaturisation. Non-scarring

Telogen effluvium (TE)

Diffuse shedding 6–12 weeks after trigger. Positive hair pull test. Self-limiting — resolves in 3–6 months. Chronic TE if >6 months. Non-scarring

Alopecia areata (AA)

Discrete round/oval patches, exclamation mark hairs at margins, normal scalp skin, nail pitting (30%). AA totalis (all scalp), AA universalis (all body hair). Autoimmune (Th1-mediated). Non-scarring, autoimmune

Tinea capitis

Scale + hair loss + pruritus, fluorescence with Wood's lamp (Microsporum), kerion (boggy mass). Mainly children. Highly infectious. Non-scarring if treated promptly

Traction alopecia

Frontal/temporal hairline recession due to tension (braids, ponytails, extensions). Marginal alopecia pattern. Can become scarring if chronic. Non-scarring if caught early

Lichen planopilaris (LPP)

Scarring alopecia — follicular erythema, peripilar scale, atrophic patches, no follicular openings. Pruritic, painful. Dermoscopy: loss of follicular ostia. Scarring → urgent dermatology

Frontal fibrosing alopecia (FFA)

Scarring alopecia — progressive frontal hairline recession, loss of eyebrows, follicular red halo, perifollicular scale. Mainly postmenopausal women. Scarring → urgent dermatology

Discoid lupus

Scarring — erythematous scaly plaques, follicular plugging, central atrophy, pigmentary changes. Sun-exposed areas. Check ANA/dsDNA. Scarring → urgent dermatology/rheum

The scarring vs non-scarring distinction dictates urgency. Non-scarring alopecia (AGA, TE, AA) is treatable and follicles remain viable. Scarring alopecia (LPP, FFA, discoid lupus, folliculitis decalvans) destroys follicles permanently — early dermatology referral arrests but does not reverse established scarring. Frontal fibrosing alopecia has increased 10-fold in incidence over the past 20 years and is now the most common form of scarring alopecia seen in dermatology — GPs must be familiar with its presentation.

Done

Diagnose

Targeted Examination — Scalp, Pattern & Systemic

Examine in good light; use a magnifying glass or dermatoscope if available.

Scalp skin assessment

Normal skin = non-scarring. Atrophic, shiny, loss of follicular openings = scarring. Scaly/inflamed = tinea/psoriasis/seborrhoeic dermatitis. Boggy/pustular = kerion/folliculitis decalvans.

Hair pull test

Grasp 40–60 hairs between thumb and index finger, apply gentle traction. >6 hairs (telogen) = positive = active shedding. Normal = <6 hairs. Positive in TE, early AA, active inflammatory alopecia.

Pattern assessment

Hamilton-Norwood scale (male AGA Grades I–VII). Ludwig scale (female: I–III). Describe exact distribution — vertex-dominant (AGA), frontal margin (FFA/traction), patchy (AA), diffuse (TE).

Exclamation mark hairs

Short hairs tapering at base (like "!") at periphery of bald patches → alopecia areata. Pathognomonic sign. Black dots = fractured hairs at surface (AA totalis).

Nails

Pitting, onycholysis, trachyonychia ("sandpaper nails") → alopecia areata (30% nail involvement). Also check for leukonychia (nutritional deficiency).

Systemic exam

Thyroid palpation, signs of hypothyroid (bradycardia, dry skin, puffiness). PCOS: hirsutism (Ferriman-Gallwey), acne, obesity. Anaemia: pallor, koilonychia. Lupus: malar rash, photosensitivity.

Lymph nodes

Cervical/occipital lymphadenopathy → tinea capitis (especially children). Generalised lymphadenopathy + hair loss → secondary syphilis, lymphoma.

Skin/body hair

Eyebrow thinning (outer third) → hypothyroid, FFA. Body hair loss → AA universalis. Eyelash loss → AA, trichotilomania.

The hair pull test takes 30 seconds and directly confirms active shedding — a negative pull test in diffuse hair loss suggests the shedding phase has ended (post-TE regrowth phase) or the patient has AGA without active telogen conversion. Exclamation mark hairs are pathognomonic for alopecia areata and their presence should prevent unnecessary investigation for systemic causes. Outer-third eyebrow loss is a classic, often missed, sign of hypothyroidism — always check eyebrows when examining the scalp.

Done

Diagnose

Investigations — Targeted Bloods & Scalp Tests

Investigate all diffuse alopecia to exclude reversible systemic causes. Do not investigate classical AGA without systemic features.

First-line bloods

FBC, ferritin, TFTs, B12, folate — mandatory in all diffuse hair loss. Iron deficiency (ferritin <30 mcg/L) and hypothyroidism are the two most common reversible causes. 25-OH vitamin D if suspected.

Ferritin interpretation

Ferritin <30 mcg/L = likely iron deficiency contributing to alopecia. Target >70 mcg/L for hair regrowth. Many labs report normal range as >12–15 — the hair threshold is higher. Treat if <70 with symptoms.

Hormone panel

Androgens: total testosterone, SHBG, free androgen index, DHEAS, LH, FSH, prolactin — in females with diffuse hair loss + features of hyperandrogenism (PCOS, adrenal). Day 2–5 of cycle.

Thyroid

TSH ± fT4 — hypothyroid and hyperthyroid both cause diffuse hair loss. TSH most sensitive. If abnormal: check TPO antibodies (autoimmune thyroiditis). Treat to TSH 1–2 mU/L.

Autoimmune screen

ANA, anti-dsDNA, complement (C3/C4) — if scarring alopecia or systemic lupus features. Anti-Ro/La if Sjögren's suspected. VDRL/RPR if syphilis possible.

Scalp biopsy

4mm punch biopsy — via dermatology for suspected scarring alopecia (LPP, discoid lupus, FFA). Horizontal sections preferred for alopecia diagnosis. Not a primary care test.

Scalp swab / Wood's lamp

Scalp swab for MC&S — if tinea capitis suspected. Wood's lamp: Microsporum fluoresces blue-green (Trichophyton does not). Confirm with scalp brushings sent for mycology.

Do NOT routinely order

Hormone panel in male AGA (not indicated), MRI head for alopecia (specialist only), scalp biopsy without dermatology involvement, zinc/copper levels (not evidence-based in routine alopecia)

The "normal" ferritin threshold used by most labs (12–15 mcg/L) is calibrated for iron-deficiency anaemia, not hair loss. Multiple studies demonstrate that hair regrowth does not occur until ferritin is >70 mcg/L in patients with alopecia — GPs must be aware of this discrepancy and treat accordingly. Hypothyroidism causes telogen effluvium and is present in 8–12% of women presenting with diffuse hair loss — missing this is a significant diagnostic error. Hormone panel in male AGA has no clinical utility — the diagnosis is clinical and treatment is empirical.

Done

Refer

Referral Criteria — Dermatology, Endocrinology, Mental Health

2WW skin cancer

2-week wait Ulcerated/bleeding scalp lesion, rapidly growing nodule, suspicious pigmented lesion, scalp patch with features of squamous cell carcinoma

Urgent dermatology

Within 2 weeks All suspected scarring alopecia (LPP, FFA, discoid lupus, folliculitis decalvans) — delay causes irreversible follicle loss. Extensive alopecia totalis/universalis.

Routine dermatology

Within 18 weeks Alopecia areata not responding to primary care treatment, suspected FFA (non-urgent if very early), traction alopecia with scarring features, diagnostic uncertainty

Paediatric dermatology / ED

Same-day / urgent Tinea capitis with kerion (same-day systemic antifungal). Tinea capitis confirmed → urgent griseofulvin/terbinafine. Notify school (infectious disease).

Endocrinology

Routine PCOS with marked hyperandrogenism + hair loss (combined OCP ± spironolactone management). Adrenal hyperandrogenism (elevated DHEAS). Resistant hypothyroidism.

Rheumatology

Within 4 weeks Suspected SLE (ANA positive + hair loss + systemic symptoms). Discoid lupus with systemic features. Co-manage with dermatology.

CAMHS / safeguarding

Urgent Trichotillomania in children with significant distress or safeguarding concerns. Adult trichotillomania — IAPT OCD pathway (HAbit Reversal Training).

Primary care manage

Male AGA (minoxidil topical, counselling, refer to trichologist/hair transplant if desired). TE post-trigger (reassurance + address cause). Iron/thyroid deficiency TE (replace and review at 3–6 months).

Frontal fibrosing alopecia (FFA) is now the most common scarring alopecia in dermatology departments in the UK — it is frequently missed in primary care as a "receding hairline" in postmenopausal women. The average delay from first GP presentation to FFA diagnosis is 2.5 years — during which time irreversible scarring progresses. Tinea capitis is highly infectious within households and schools — public health notification and household screening are required. Children need 6 months of griseofulvin or 4 weeks of terbinafine (off-label in <4 years).

Done

Treat

Pharmacological Treatment — Condition-Specific Pathway

Address reversible causes first. Condition-specific pharmacological treatments below.

Male AGA

Minoxidil 5% topical OTC

Apply 1 ml to dry scalp BD. Results at 4–6 months. Continue indefinitely — stops on cessation. OR oral minoxidil 2.5 mg OD (off-label, effective). Finasteride 1 mg OD (prescription, private only NHS) — check PSA baseline.

Female AGA (FPHL)

Minoxidil 2% topical OTC

Apply 1 ml BD to affected areas. 5% minoxidil also effective but more side effects (facial hypertrichosis). Spironolactone 100–200 mg OD (off-label, antiandrogen) — via specialist or GP with monitoring (K+, BP).

Alopecia areata (limited)

Potent topical corticosteroid

Betamethasone valerate 0.1% solution or clobetasol propionate 0.05% scalp application OD for 3–6 months. Intralesional triamcinolone 10 mg/ml — specialist procedure. Spontaneous remission in 50% within 12 months.

Tinea capitis

Griseofulvin or Terbinafine

Child: Griseofulvin 10–20 mg/kg/day × 6–8 weeks (Microsporum); OR Terbinafine 62.5–250 mg OD × 4 weeks (Trichophyton). Adult: Terbinafine 250 mg OD × 4 weeks. Plus selenium sulfide/ketoconazole shampoo to reduce spore shedding.

Telogen effluvium

Treat underlying cause

Iron: ferrous sulfate 200 mg TDS if ferritin <70. Thyroid: levothyroxine titrated to TSH 1–2. B12: hydroxocobalamin IM. Reassure: self-limiting, 6–12 months recovery. No role for minoxidil.

Scarring alopecia

Dermatology-led Rx

LPP/FFA: hydroxychloroquine 200–400 mg OD (specialist). Topical steroids. Pioglitazone 15 mg OD (off-label, FFA). Discoid lupus: hydroxychloroquine + sunscreen. Arrest not reversal is the goal.

Minoxidil's mechanism involves prolonging the anagen (growth) phase and increasing follicle size — it does not treat the androgenetic cause. Discontinuation leads to reversal of benefit within 3–4 months, making it a lifelong commitment. Finasteride is licensed for male AGA only (not female) — it reduces DHT by 70% and halts AGA in 83% of men (NNT 3.5 for hair count improvement). Post-finasteride syndrome (persistent sexual dysfunction) is a rare but real adverse effect — counsel patients explicitly. Spironolactone for FPHL is commonly used off-label in the UK — monitor potassium and blood pressure.

Done

Lifestyle

Non-Pharmacological Interventions & Psychological Support

Nutritional optimisation Target ferritin >70 mcg/L, normal TSH, normal B12/folate. Iron-rich diet (red meat, lentils, dark leafy greens). Vitamin C with iron enhances absorption. Avoid tea/coffee with iron-containing meals.

Avoid hair trauma Reduce tight hairstyles (ponytails, braids, extensions, buns) — all cause traction alopecia. Heat styling, bleaching, and chemical relaxers damage hair shaft. Advise: loose styles, wide-toothed combs on wet hair, silk pillowcase.

Gentle hair washing Wash every 2–3 days (not daily) with gentle shampoo. Massage scalp to improve circulation. Air dry rather than heat dry. Seborrhoeic dermatitis (dandruff) worsens some alopecias — use ketoconazole 2% shampoo twice weekly if present.

Stress reduction Psychological stress is a proven telogen effluvium trigger via cortisol-mediated anagen-to-telogen shift. CBT, mindfulness, exercise all reduce cortisol. Address underlying stressors. Mental health support if severe anxiety/depression.

Psychological support 40% of women with alopecia develop anxiety or depression. Validate the psychological impact explicitly. Refer to IAPT for CBT. Alopecia UK charity offers peer support, wigs advice, helpline. NHS wig provision available for alopecia totalis/universalis.

NHS wig provision NHS wigs available free on prescription for medically indicated alopecia (alopecia areata totalis, chemotherapy-induced). GP to complete FP10 prescription. Surgical fitter referral via PALS. Human hair wigs available via voucher scheme.

Sunscreen (FFA/discoid lupus) UV light triggers FFA and discoid lupus progression. Daily SPF 50+ on scalp and face. Hat use strongly encouraged. Refer to occupational health if outdoor worker.

Platelet-rich plasma (PRP) PRP scalp injections — emerging evidence for AGA and AA (3 RCTs positive). Not currently NHS-funded. Private cost £300–600/session. Patients may ask — evidence is promising, endorse as an option. 3 sessions 4–6 weeks apart.

Hair loss carries a psychological burden equivalent to that of chronic pain — studies consistently show quality-of-life scores in alopecia areata patients comparable to patients with psoriasis and chronic eczema. Validating this impact explicitly in the consultation improves patient satisfaction and reduces re-consultation. Traction alopecia is preventable and reversible if caught early — becoming the most common alopecia in Black women in the UK, with cultural and social dimensions that require sensitive discussion. NHS wig prescribing is an entitlement that is significantly under-utilised — GPs should be aware of the process.

Done

Safety

Follow-Up, Monitoring & Safety-Netting

6–8 weeks

Review response to iron/thyroid replacement in TE — bloods improving? Review traction alopecia if advised to change hair practices. Monitor for minoxidil side effects (scalp irritation, facial hypertrichosis in women). Confirm tinea capitis treatment compliance and school notification.

3–4 months

Recheck ferritin, TSH in TE — target ferritin >70. Minoxidil: early response may be seen (reduced shedding before regrowth). Alopecia areata: reassess extent, consider escalation or referral. Hormone results review for FPHL.

6–12 months

TE recovery expected — if not resolved, reassess diagnosis (FPHL? ongoing trigger?). AGA: photo documentation to assess treatment response. Annual review of all chronic alopecia medications.

Monitoring — Finasteride

PSA baseline before starting, annual PSA while on treatment (raises PSA interpretation threshold — adjust reference range). Counsel: rare risk of post-finasteride syndrome. Annual erectile function enquiry.

Monitoring — Spironolactone

U&E + BP at 1 month, 3 months, then 6-monthly. Target K+ <5.5. Contraindicated in CKD, ACE inhibitor combination (hyperK risk). Adequate contraception required (teratogenic).

Safety-net same-day GP

Rapid progression of hair loss over days/weeks, new scalp ulceration or bleeding lesion, systemic symptoms developing (fever, weight loss, rash), worsening after treatment initiation

Re-refer if

Scarring features develop in previously non-scarring alopecia, AGA not responding after 12 months of minoxidil, new neurological symptoms in patient with SLE, ferritin/TSH corrected but no regrowth after 9 months

The clinical response to iron replacement in TE can take 6–9 months to manifest as visible hair regrowth — patients require clear explanation and support through this waiting period to prevent premature abandonment of treatment. Minoxidil "shedding" in the first 2–4 weeks of treatment (paradoxical telogen effluvium induction) frequently causes patients to discontinue — proactively warn about this. Finasteride raises PSA levels — a man on finasteride with a PSA within the "normal" range may actually have an elevated underlying PSA. The guideline-recommended correction factor is to double the measured PSA when interpreting results in finasteride users.