Hair Loss (Alopecia) — Causes, Types & Treatment Options — Causes, Diagnosis & When to See a Doctor | MyMedicPlus

Hair loss (alopecia) encompasses any significant reduction in the number or density of scalp hairs. The average person has approximately 100,000 hair follicles on the scalp and loses 50–100 hairs per day as part of the normal hair growth cycle — each follicle cycling independently through anagen (active growth, lasting 2–7 years), catagen (transition, lasting 2–3 weeks), and telogen (resting and shedding, lasting 2–4 months) phases. Hair loss becomes clinically significant when this natural cycle is disrupted — either through premature follicle miniaturisation (as in androgenetic alopecia), synchronised mass shedding (telogen effluvium), follicle destruction (scarring alopecia), or autoimmune attack (alopecia areata). Androgenetic alopecia (male or female pattern baldness) is the most common form, affecting approximately 50% of men by age 50 and 25% of women by the same age, with a steadily increasing prevalence thereafter. The impact of hair loss extends well beyond cosmetics — hair carries profound cultural and personal significance, and alopecia of any cause is frequently associated with significant psychological distress, depression, reduced self-esteem, and social withdrawal, effects that are independent of the degree of hair loss. Recognition of hair loss type and cause enables appropriate investigation, evidence-based treatment, and realistic prognostic counselling.

Androgenetic alopecia (AGA) is the most prevalent cause, driven by genetically determined follicular sensitivity to dihydrotestosterone (DHT) — a potent androgen metabolite of testosterone converted by 5-alpha-reductase. In men, AGA produces a characteristic receding frontal hairline and vertex thinning (Hamilton-Norwood pattern); in women, diffuse thinning predominantly at the crown with preservation of the frontal hairline (Ludwig pattern). Telogen effluvium (TE) causes diffuse shedding starting 2–4 months after a systemic physiological stressor — acute illness with high fever, major surgery, significant haemorrhage, childbirth (postpartum alopecia affects up to 45% of new mothers), extreme rapid weight loss (crash dieting), or severe psychological stress. Chronic telogen effluvium may be sustained by ongoing nutritional deficiency or systemic illness. Alopecia areata (AA) is an organ-specific autoimmune condition in which T-lymphocytes attack the hair follicle bulb, producing patchy, well-demarcated, non-scarring hair loss that can progress to total scalp hair loss (alopecia totalis) or complete body hair loss (alopecia universalis). Iron deficiency — even without overt anaemia (low ferritin below 30–70 mcg/L) — is one of the most common and most reversible causes of hair loss, particularly in menstruating women and vegetarians. Hypothyroidism causes diffuse hair thinning and loss of the outer third of the eyebrows — both reverse with adequate thyroid hormone replacement. Hyperthyroidism similarly causes diffuse thinning. Medications that commonly cause hair loss (drug-induced alopecia) include cytotoxic chemotherapy, anticoagulants (warfarin, heparin), retinoids (isotretinoin, acitretin), some antidepressants (SSRIs, lithium), and antihypertensives (beta-blockers, ACE inhibitors). Traction alopecia results from chronic mechanical tension on the hair shaft from tight hairstyles — braids, weaves, tight ponytails, and hair extensions. Tinea capitis (scalp ringworm from Trichophyton fungi) causes patchy hair loss with broken hairs, scalp scaling, and sometimes kerion formation, and is most common in children. Scarring (cicatricial) alopecias — including lichen planopilaris, discoid lupus erythematosus, and frontal fibrosing alopecia — permanently destroy follicles through inflammatory infiltrate; early treatment is essential to limit progression.

Seek prompt medical evaluation — ideally within 2–4 weeks — for any of the following features of hair loss that suggest systemic disease, active inflammatory destruction, or rapidly progressing pathology. Sudden diffuse shedding of large amounts of hair daily (more than 200–300 hairs per day on the pull test or by visual counting in a single washing) occurring over weeks warrants investigation for thyroid disease, iron deficiency, or autoimmune conditions. Patchy hair loss with scalp changes — redness, scaling, crusting, pustules, pain, or burning sensations — suggests scarring alopecia (lichen planopilaris, frontal fibrosing alopecia) or infectious tinea capitis, both of which cause permanent follicle destruction if untreated. Scarring alopecia with smooth, shiny, atrophic scalp skin without follicular openings is irreversible — early treatment is critical. Hair loss associated with loss of eyebrows, eyelashes, or other body hair suggests alopecia areata universalis or a systemic endocrine problem. Hair loss combined with systemic symptoms — significant fatigue, weight change, cold or heat intolerance, palpitations, menstrual irregularity, or skin changes — requires a targeted blood test panel to identify the underlying medical cause. Frontal hairline recession progressing rapidly in a woman with facial hair growth and acne raises concern for polycystic ovary syndrome (PCOS) or other androgen excess states requiring hormonal evaluation. Any hair loss causing significant psychological distress, interfering with self-image, or leading to avoidance of social activity warrants early dermatological assessment.

A detailed clinical history establishes the type of hair loss (diffuse versus patterned versus patchy), duration and rate of progression, presence of scalp symptoms (itch, burn, pain, scaling), shedding pattern (on the pillow, in the shower, on clothing), family history of alopecia, recent physical or emotional stressors, dietary habits including restrictive diets, medication list (including supplements and hormonal contraceptives), and associated systemic symptoms. The pull test — grasping 40–60 hairs between the thumb and index finger and exerting traction — assesses active shedding; more than 6 hairs extracted indicates active telogen effluvium or alopecia areata. Dermoscopy (trichoscopy) — magnified examination of the scalp and follicles using a handheld or video dermoscope — identifies miniaturised follicles (AGA), yellow dots (alopecia areata), peripilar casts (scarring alopecia), and fungal spores (tinea capitis). A targeted blood panel for hair loss includes: thyroid function (TSH, free T4), ferritin (the most sensitive iron store marker; target above 70 mcg/L for hair growth), full blood count (anaemia), serum iron and transferrin saturation, zinc, vitamin B12, vitamin D, DHEAS and total testosterone (in women with features of androgen excess), prolactin, and sex hormone binding globulin (SHBG). ANA and anti-ds-DNA are ordered when lupus is suspected. Scalp biopsy — a 4mm punch biopsy from an active lesion — provides definitive histological diagnosis in scarring alopecia, advanced alopecia areata, and uncertain cases. Scalp scraping and microscopy or PCR identifies tinea capitis.

Treatment selection depends entirely on the cause, type, and duration of hair loss. Telogen effluvium most commonly resolves spontaneously within 6–12 months once the triggering stressor has passed, without specific treatment — correcting any identified nutritional deficiency (iron, zinc, biotin) accelerates recovery, and reassurance is an important aspect of management. Iron deficiency is treated with oral iron supplementation — ferrous sulphate 200mg two to three times daily with vitamin C to enhance absorption — for at least 3–6 months after ferritin levels normalise above 70 mcg/L. Thyroid disease correction with levothyroxine for hypothyroidism typically reverses hair loss within 6–12 months of achieving adequate thyroid hormone levels. Androgenetic alopecia in men is treated with topical minoxidil (2% or 5% solution or foam applied daily to the scalp) — shown to slow progression and promote regrowth in 60–70% of users — and oral finasteride (1mg daily), a 5-alpha-reductase inhibitor that reduces scalp DHT by 65% and achieves regrowth or stabilisation in approximately 85% of men. Oral minoxidil (at low doses 0.5–2.5mg daily) is an increasingly used systemic option. In women, topical minoxidil 5% is the primary pharmacological option. Alopecia areata is treated with intralesional corticosteroid injections (triamcinolone acetonide) into the patches for limited disease — achieving regrowth in 60–70% of cases; extensive disease is treated with topical immunotherapy (diphenylcyclopropenone or diphencyprone), oral JAK inhibitors (baricitinib, ritlecitinib — approved for severe alopecia areata), or systemic corticosteroids. Tinea capitis requires systemic antifungal therapy (terbinafine, itraconazole, or griseofulvin) as topical agents do not penetrate the hair shaft. Scarring alopecia requires aggressive early immunosuppression to halt progression — hydroxychloroquine, ciclosporin, or biologics depending on the type.

Maintain a nutritionally complete diet with sufficient protein (at least 0.8–1.0g per kg body weight daily — hair is made of keratin, a protein, and inadequate protein intake causes diffuse shedding), iron (from red meat, lentils, beans, tofu, leafy greens, fortified cereals — consume with vitamin C to maximise non-haem iron absorption), zinc (meat, shellfish, nuts, seeds), and biotin (eggs, nuts, wholegrains) — targeted supplementation rather than multivitamin guesswork is more effective when deficiencies are confirmed by testing. Avoid crash dieting, very low calorie diets, or elimination of food groups, all of which trigger telogen effluvium through nutritional stress within 2–4 months. Protect the hair shaft from chemical and thermal damage — limit bleaching, perming, heat styling (straighteners, curling irons), and harsh detergent shampoos; use heat protectant products and moisturising conditioners. Avoid hairstyles that create sustained tension on follicles — tight braids, weaves, cornrows, and high ponytails cause traction alopecia, which becomes irreversible with prolonged or repeated trauma. Handle hair gently when wet, as wet hair is more susceptible to shaft fracture. Manage chronic stress with exercise, mindfulness, adequate sleep, and professional psychological support when needed — chronic psychological stress perpetuates telogen effluvium. Annual blood tests including thyroid function and ferritin allow early detection of the most common reversible causes of hair loss before significant thinning occurs.

Schedule a GP appointment within 2–4 weeks for any of the following: noticeable hair thinning or diffuse shedding of more than 150 hairs per day that has persisted more than 4–8 weeks; sudden patchy hair loss affecting one or more clearly defined round areas; hair loss accompanied by scalp symptoms such as redness, scaling, pain, or burning; hair loss combined with systemic symptoms — significant fatigue, weight change, temperature intolerance, or menstrual irregularity — that suggest an underlying medical cause; or hair loss causing clinically significant psychological distress or social avoidance. Request dermatology or trichology referral for complex cases, suspected scarring alopecia (which requires early intervention to prevent permanent follicle destruction), alopecia totalis or universalis, or failure to respond to first-line pharmacological treatment. Children with patchy hair loss with scalp scaling, broken hairs, or pustules should be assessed promptly for tinea capitis, which is highly contagious in school settings and requires systemic antifungal treatment. Do not self-treat with over-the-counter supplements or shampoos for more than 4–8 weeks without a diagnosis — identifying and treating the specific cause is far more effective than non-targeted supplementation. Early assessment and treatment before significant follicle miniaturisation or destruction occurs leads to much better hair regrowth outcomes.