ICD-10 hair loss coding underpins how alopecia diagnoses are recorded, reported, and reimbursed across UK secondary care settings. Whether you are a clinician seeking accurate classification or a patient trying to understand your diagnosis, knowing the relevant ICD-10 codes — from androgenetic alopecia (L64) to scarring alopecias (L66) — is essential. This article explains the key ICD-10 codes used for hair loss in the UK, outlines the main diagnostic categories, describes how clinicians assess and record these conditions, and covers NHS treatment pathways and referral guidance.

ICD-10 Codes Used to Classify Hair Loss in the UK

Hair loss ICD-10 codes fall within the L60–L75 block of Chapter XII, with L63 (alopecia areata), L64 (androgenetic alopecia), L65 (non-scarring hair loss), and L66 (scarring alopecia) being the most frequently used in UK secondary care.

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The International Classification of Diseases, 10th Revision (ICD-10) is the coding system used in UK hospitals and secondary care settings to record diagnoses consistently for admitted patient care, mortality statistics, and secondary uses such as reimbursement and epidemiological research. It is important to note that UK primary care (GP) systems such as EMIS and SystmOne use SNOMED CT as the mandated clinical terminology; ICD-10 codes are generated through mapping for secondary uses rather than being entered directly by GPs. For hair loss conditions, the relevant ICD-10 codes fall within Chapter XII (Diseases of the skin and subcutaneous tissue), specifically under the block L60–L75 (Disorders of skin appendages).

The most frequently used ICD-10 codes for hair loss include:

• L63 – Alopecia areata (L63.0 alopecia areata; L63.1 alopecia totalis; L63.2 alopecia universalis; L63.8 other alopecia areata; L63.9 alopecia areata, unspecified)

• L64 – Androgenic alopecia (male-pattern and female-pattern hair loss; note that clinicians commonly use the term 'androgenetic alopecia', though ICD-10 uses 'androgenic')

• L65 – Other non-scarring hair loss (including L65.0 telogen effluvium; L65.1 anagen effluvium; L65.8 other specified non-scarring hair loss; L65.9 non-scarring hair loss, unspecified)

• L66 – Cicatricial alopecia (scarring hair loss, including lichen planopilaris and discoid lupus erythematosus-related alopecia)

• L67 – Hair colour and hair shaft abnormalities

Accurate ICD-10 coding in secondary care is essential for clinical record-keeping, NHS England data reporting, hospital reimbursement, and epidemiological audit. Understanding these codes helps patients appreciate why their diagnosis is recorded in a specific way and how it contributes to the care they receive. Authoritative coding guidance is published by NHS England (Classifications Service) and the World Health Organization (WHO ICD-10, Chapter XII).

Common Types of Hair Loss and Their Diagnostic Categories

Hair loss is broadly classified as non-scarring (e.g., androgenetic alopecia L64, alopecia areata L63, telogen effluvium L65.0) or scarring (L66); scarring alopecias carry a worse prognosis due to permanent follicular destruction.

Hair loss — medically termed alopecia — encompasses a broad spectrum of conditions, each with distinct underlying mechanisms, clinical presentations, and ICD-10 classifications. Broadly, hair loss is divided into non-scarring (non-cicatricial) and scarring (cicatricial) forms, a distinction that carries significant prognostic and therapeutic implications.

Non-scarring alopecias are the most prevalent and include:

• Androgenetic alopecia (L64): The commonest form of hair loss, affecting a significant proportion of men and women (NICE CKS estimates up to 50% of men by age 50). It is driven by dihydrotestosterone (DHT) sensitivity in genetically predisposed hair follicles, leading to progressive miniaturisation. ICD-10 uses the term 'androgenic alopecia (L64)', whilst the clinical literature commonly uses 'androgenetic alopecia'; both terms refer to the same condition.

• Alopecia areata (L63): An autoimmune condition in which T-lymphocytes target hair follicles, producing patchy, well-demarcated hair loss. It can progress to total scalp hair loss (alopecia totalis, L63.1) or whole-body hair loss (alopecia universalis, L63.2).

• Telogen effluvium (L65.0): A diffuse, often temporary shedding triggered by physiological stressors such as childbirth, significant illness, nutritional deficiency, or major surgery. Hair follicles prematurely enter the telogen (resting) phase.

• Anagen effluvium (L65.1): Diffuse hair loss occurring during the active growth (anagen) phase, most commonly associated with chemotherapy or other cytotoxic agents.

Scarring alopecias (L66) are less common but more serious, as permanent follicular destruction occurs. Conditions such as lichen planopilaris, frontal fibrosing alopecia, and discoid lupus erythematosus fall into this category. Early recognition is critical, as prompt treatment may slow or halt progression.

Traction alopecia — caused by prolonged mechanical tension on hair — is typically non-scarring in its early stages and is coded L65.8 (other specified non-scarring hair loss). If long-standing scarring has occurred, coding under L66.8 or L66.9 may be more appropriate; L66.3 (perifolliculitis capitis abscedens) should not be used for traction alopecia.

How UK Clinicians Diagnose and Record Hair Loss

UK clinicians diagnose hair loss through history, clinical examination, trichoscopy, and targeted blood tests including FBC, serum ferritin, and TFTs; primary care records diagnoses in SNOMED CT, whilst secondary care applies ICD-10 codes directly.

Diagnosing hair loss in UK clinical practice involves a structured approach combining detailed history-taking, clinical examination, and targeted investigations, guided by NICE Clinical Knowledge Summaries (CKS), British Association of Dermatologists (BAD) guidelines, and Primary Care Dermatology Society (PCDS) guidance.

During the consultation, clinicians typically assess:

• Onset and pattern of hair loss (diffuse, patchy, or patterned)

• Associated symptoms such as scalp itching, burning, or tenderness

• Medical history including thyroid disease, autoimmune conditions, and recent illness

• Medication history, as numerous drugs — including anticoagulants, retinoids, antithyroid agents, and certain antihypertensives — are associated with drug-induced alopecia (coded under L65.8 or relevant T-codes for adverse drug effects)

• Nutritional status, particularly iron and ferritin levels where clinically indicated

• Family history of hair loss

Clinical examination includes assessment of the hair pull test, scalp surface, and hair shaft characteristics. Trichoscopy (dermoscopy of the scalp) is increasingly used in secondary care to differentiate conditions without the need for biopsy. Where scarring alopecia is suspected, a scalp punch biopsy may be required for histological confirmation.

Blood investigations commonly requested in line with UK guidance (NICE CKS, PCDS) include full blood count (FBC), serum ferritin, and thyroid function tests (TFTs). Vitamin D, zinc, and broader micronutrient testing should be reserved for cases where clinical features suggest deficiency, rather than being performed routinely. Androgen and hormonal testing in women should be targeted to those with clinical features of hyperandrogenism (e.g., hirsutism, menstrual irregularity) or suspected polycystic ovary syndrome (PCOS), in line with NICE CKS guidance, rather than offered routinely.

Regarding clinical recording: in primary care, diagnoses are recorded using SNOMED CT in GP systems (EMIS, SystmOne), with mapping to ICD-10 supporting secondary uses. In secondary care, ICD-10 codes are applied directly for hospital episode statistics, reimbursement, and audit. OPCS-4 codes are used for procedures (e.g., scalp biopsy) in hospital settings.

NHS Treatment Pathways for Hair Loss Conditions

NHS treatment depends on diagnosis and clinical need; androgenetic alopecia is generally considered cosmetic and not routinely funded, whilst alopecia areata may be treated with corticosteroids or baricitinib subject to NICE commissioning criteria.

Treatment for hair loss on the NHS is largely determined by the underlying diagnosis, its impact on the patient's quality of life, and whether the condition is considered medically necessary or cosmetic. It is important to note that many hair loss treatments are not routinely funded by the NHS, particularly those for androgenetic alopecia, which is generally classified as a cosmetic concern.

Androgenetic alopecia (L64): There is currently no NICE Technology Appraisal recommending routine NHS prescribing of finasteride or minoxidil for pattern hair loss, and many Integrated Care Boards (ICBs) do not routinely commission these treatments for cosmetic indications. Topical minoxidil (2% or 5% solution) is available over the counter without prescription. Oral minoxidil is used off-label for hair loss and is not routinely commissioned on the NHS; specialist oversight is required if considered.

Finasteride (1 mg daily) is licensed for men only and works by inhibiting the 5-alpha reductase enzyme, thereby reducing DHT levels at the follicle. Patients must be counselled thoroughly about its safety profile, in line with the MHRA Drug Safety Update and the UK Summary of Product Characteristics (SmPC for Propecia/finasteride 1 mg): risks include sexual dysfunction (which may persist after stopping treatment), psychiatric effects including depression and, rarely, suicidal ideation, and the requirement for long-term use to maintain benefit. Finasteride is contraindicated in pregnancy, and women who are pregnant or may become pregnant should not handle crushed or broken tablets. Suspected adverse reactions should be reported via the MHRA Yellow Card scheme (yellowcard.mhra.gov.uk).

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Alopecia areata (L63): NHS treatment options include potent topical corticosteroids, intralesional corticosteroid injections (typically triamcinolone acetonide), and contact immunotherapy in specialist centres. Baricitinib (Olumiant), a JAK1/JAK2 inhibitor, has received MHRA and EMA approval for severe alopecia areata in adults — a significant therapeutic advance. Prescribing is initiated by specialists, and patients require monitoring for serious infections, venous thromboembolism (VTE), and laboratory parameters as detailed in the UK SmPC. NHS commissioning is subject to the current NICE Technology Appraisal on baricitinib for severe alopecia areata; clinicians and patients should consult the most recent NICE guidance for eligibility criteria and funding status. Suspected adverse reactions should be reported via the MHRA Yellow Card scheme.

Telogen effluvium (L65.0): Management focuses on identifying and addressing the underlying trigger. Nutritional deficiencies should be corrected where identified, and patients reassured that spontaneous recovery typically occurs within 6–12 months. No specific pharmacological treatment is routinely recommended.

Scarring alopecias (L66): Treatment aims to suppress inflammation and halt progression, using agents such as hydroxychloroquine, topical or systemic corticosteroids, and immunosuppressants, guided by dermatology specialists and BAD guidelines.

When to Seek a GP or Dermatology Referral for Hair Loss

Patients should see their GP for sudden, patchy, or rapidly progressive hair loss, scalp symptoms suggesting scarring, associated systemic features, or hair loss in children; suspected scarring alopecia warrants prompt dermatology referral.

Whilst hair loss is rarely a medical emergency, certain features warrant prompt assessment by a GP or specialist. Understanding when to seek help ensures that serious underlying conditions are not missed and that treatment — where available — is initiated in a timely manner.

Patients should contact their GP if they notice:

• Sudden or rapid hair loss, particularly if diffuse or occurring in large clumps

• Patchy hair loss with well-defined borders, which may suggest alopecia areata

• Scalp symptoms such as persistent itching, burning, pain, or visible scaling, which may indicate an inflammatory or scarring process

• Signs that may suggest scarring alopecia, including perifollicular redness or scaling, tenderness, or visible loss of follicular openings — these warrant prompt dermatology referral

• Associated systemic symptoms such as fatigue, weight change, or cold intolerance, which could point to thyroid dysfunction or other systemic disease

• Hair loss following a new medication, as drug-induced alopecia should be reviewed and the causative agent reconsidered where clinically appropriate; suspected adverse drug reactions should be reported via the MHRA Yellow Card scheme

• Hair loss in children, which always warrants medical evaluation to exclude tinea capitis (fungal infection, coded B35.0) or other conditions, in line with NICE CKS guidance on tinea capitis

GPs should consider urgent or routine dermatology referral in cases of suspected scarring alopecia, rapidly progressive alopecia areata, or where the diagnosis remains uncertain after initial assessment. Referral thresholds are outlined in NICE CKS and PCDS guidance. The 2-week wait pathway is not typically applicable to hair loss unless an underlying malignancy is suspected.

From a patient safety perspective, self-diagnosing using ICD-10 codes or online resources is not a substitute for professional clinical assessment. Hair loss can be a marker of significant systemic disease, and a thorough evaluation by a qualified clinician remains the cornerstone of safe, effective management. Patients experiencing significant psychological distress related to hair loss should also be supported; referral to psychological services or patient support organisations such as Alopecia UK may be beneficial. Further patient information is available on the NHS website (nhs.uk: Hair loss).

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