Hair Loss (Alopecia) — Causes, Types, Minoxidil & Treatment Guide — Symptoms, Causes & Treatment | MyMedicPlus

Hair loss (alopecia) is the thinning or complete loss of hair from the scalp or body, affecting up to 50% of men and 40% of women by age 50–70. Androgenetic alopecia (male and female pattern hair loss) is the most common cause, affecting approximately 50% of men over 50 and 25–40% of women of similar age. Hair loss can be temporary (telogen effluvium, alopecia areata) or permanent (androgenetic alopecia, cicatricial alopecia). The psychological impact of hair loss is significant, with studies showing high rates of depression, anxiety, and social withdrawal, particularly in women. The normal hair cycle consists of anagen (growth, 2–7 years), catagen (regression, 2–3 weeks), and telogen (resting, 3 months), with 50–100 hairs shed daily as normal. Any disruption to this cycle can cause increased shedding or reduced regrowth. Hair loss classifications include non-scarring (follicle intact, potentially reversible — androgenetic alopecia, alopecia areata, telogen effluvium) and scarring or cicatricial alopecia (follicle permanently destroyed — lichen planopilaris, discoid lupus, central centrifugal cicatricial alopecia) which requires urgent diagnosis and treatment.

Androgenetic alopecia results from genetic sensitivity of hair follicles to dihydrotestosterone (DHT), causing follicular miniaturization and progressive thinning. Telogen effluvium is diffuse shedding triggered by physical or emotional stressors: severe illness, major surgery, childbirth (postpartum telogen effluvium), crash dieting, iron deficiency anemia, hypothyroidism, or medication side effects (chemotherapy, isotretinoin, heparin). Alopecia areata is autoimmune — T-lymphocytes attack hair follicles causing patchy loss. Tinea capitis (scalp ringworm) causes inflammatory hair loss in children. Traction alopecia results from hairstyles placing prolonged tension on follicles. Medications commonly causing telogen effluvium include anticoagulants (heparin, warfarin), antithyroid drugs, beta-blockers, ACE inhibitors, mood stabilizers (lithium, valproate), retinoids (high-dose vitamin A), and cholesterol-lowering fibrates. Heavy metal toxicity (thallium, arsenic, mercury) causes hair loss alongside systemic toxicity. Trichotillomania (compulsive hair pulling) is a psychiatric condition causing irregular patchy alopecia with broken hairs of varying lengths.

Male pattern baldness (Hamilton-Norwood scale) causes recession of the hairline at the temples and thinning at the crown, which may coalesce to total vertex baldness. Female pattern hair loss (Ludwig scale) causes diffuse thinning at the crown with preservation of the frontal hairline. Telogen effluvium presents as excessive shedding (more than 100 hairs per day) with diffuse thinning and widening of the parting. Alopecia areata presents as smooth, oval patches of hair loss with exclamation mark hairs at the margin; it may progress to total scalp (alopecia totalis) or entire body hair loss (alopecia universalis). The male-pattern baldness Hamilton-Norwood scale grades from Type I (minimal hairline recession) to Type VII (only a band of hair on the sides and back). Diffuse hair thinning in female-pattern loss may be subtle initially — widening of the central part is often the first noticeable sign. Trichoscopy allows reliable early identification of miniaturized hair shafts and yellow dots (characteristic of androgenetic alopecia) before clinically obvious thinning.

Clinical history including duration, pattern, associated symptoms (scalp itching, scaling), family history, medication use, recent illness or major life stressors, and nutritional history guides diagnosis. The pull test (gentle traction of 40–60 hairs — normally fewer than 6 release) assesses active shedding. Trichoscopy (dermoscopy of the scalp) identifies miniaturized hair shafts, yellow dots, and empty follicular ostia characteristic of androgenetic alopecia, or broken hairs and dystrophic anagen bulbs in alopecia areata. Blood tests screen for thyroid function (TSH), iron studies (ferritin, TIBC), CBC, ANA, androgens (in women with virilizing symptoms), and vitamin D. Scalp biopsy differentiates scarring from non-scarring alopecia.

Topical minoxidil (2% women, 2–5% men) applied twice daily to the scalp is the most widely used treatment for androgenetic alopecia — it prolongs the anagen phase and increases follicle size. Results are visible after 6–12 months and require continuous use to maintain. Oral minoxidil (1–5 mg daily) is increasingly used off-label with excellent efficacy. Finasteride (1 mg daily) blocks 5-alpha-reductase to reduce DHT — highly effective in men (80% see benefit), not approved in premenopausal women due to birth defect risk. Dutasteride (0.5 mg daily) is an alternative with higher 5-alpha-reductase inhibition. JAK inhibitors (baricitinib, ritlecitinib, deuruxolitinib) are FDA-approved for alopecia areata with significant evidence. Hair transplant surgery (FUE, FUT) provides permanent cosmetic improvement for androgenetic alopecia. Spironolactone (100–200 mg daily) is used off-label in women with female-pattern hair loss, acting as an anti-androgen. Low-level laser therapy (LLLT) using devices emitting red light at 630–670 nm has FDA clearance for promoting hair growth in androgenetic alopecia through photobiomodulation effects on follicles. Platelet-rich plasma (PRP) injections deliver concentrated growth factors into the scalp to stimulate follicle activity — 3–6 sessions typically required with maintenance injections every 3–6 months.

Significant psychological complications including depression, anxiety, reduced self-esteem, and social withdrawal affect a large proportion of people with hair loss, particularly women and those with alopecia areata. Quality of life studies show impairment comparable to serious chronic diseases. Alopecia totalis and universalis cause loss of eyebrow and eyelash protection against foreign bodies and UV radiation. Cicatricial (scarring) alopecias permanently destroy hair follicles and require immunosuppressive treatment to halt progression. Untreated telogen effluvium in the context of nutritional deficiency (particularly iron deficiency) may not resolve without addressing the underlying deficiency.

Correct underlying nutritional deficiencies — particularly iron deficiency, which is a common and reversible cause of telogen effluvium in women of reproductive age. Avoid tight hairstyles (braids, ponytails, extensions) to prevent traction alopecia. Minimize thermal damage and chemical treatments. Manage thyroid disease, hormonal disorders, and other systemic conditions contributing to hair loss. Reduce acute stressors where possible. For androgenetic alopecia, early treatment initiation with minoxidil preserves more hair follicles than delaying until substantial thinning occurs. Scalp protection from UV light and topical agents in oily scalp conditions also supports hair follicle health.

See a GP if you notice: sudden or patchy hair loss (smooth round bald patches — possible alopecia areata requiring treatment with steroid injections or immunotherapy); rapid or diffuse shedding across the whole scalp starting 2-3 months after illness, surgery, or extreme stress (telogen effluvium — may indicate iron deficiency, thyroid disease, or nutritional deficiency requiring blood tests); hair loss with scalp scaling, redness, or scarring (scarring alopecia — requires urgent dermatology referral as hair loss may be permanent if untreated); hair loss with other symptoms such as fatigue, weight changes, or irregular periods. Refer to a dermatologist or trichologist for: progressive pattern hair loss not responding to 6 months of minoxidil; alopecia areata with over 50% scalp involvement; and consideration of platelet-rich plasma, JAK inhibitors (baricitinib), or hair transplantation.