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Hair Loss Causes โ€” Why It Happens and What Actually Helps (2026)

The most common causes of hair loss, how to identify your type, and evidence-based treatments that work. Updated January 2026.
๐Ÿ“… Updated January 2026โฑ 8 min read๐Ÿ‘ค Dr. Priya Sharma, MDโœ“ Medically Reviewed
Key Takeaways
  • Androgenetic alopecia (male/female pattern) accounts for 90% of hair loss in adults
  • Telogen effluvium โ€” shedding after stress, illness, or childbirth โ€” typically reverses within 6 months
  • Iron deficiency and vitamin D deficiency are the most common nutritional causes โ€” both treatable
  • Minoxidil (Regaine) is the most evidence-backed over-the-counter treatment
  • Finasteride (prescription for men) is the most effective pharmacological treatment for pattern hair loss

Types of Hair Loss

Hair loss (alopecia) has many causes, and identifying the correct type is essential before choosing treatment. The most important differentiation is whether the loss is from the follicle itself being destroyed (scarring/cicatricial โ€” permanent) or the follicle being suppressed (non-scarring โ€” potentially reversible).

90%
of hair loss is androgenetic alopecia (pattern hair loss)
2โ€“3 mo
Delay between trigger and telogen effluvium shedding
6โ€“9 mo
Typical recovery time from telogen effluvium

The Most Common Causes

1. Androgenetic Alopecia (Pattern Hair Loss) โ€” 90% of Cases

Caused by sensitivity of hair follicles to DHT (dihydrotestosterone). In men: receding temples and vertex thinning (Hamilton-Norwood scale). In women: diffuse thinning at the crown with preserved frontal hairline (Ludwig scale). Genetic, progressive, but manageable.

2. Telogen Effluvium โ€” Stress Shedding

After any significant physiological stress (childbirth, surgery, illness, severe psychological stress, extreme calorie restriction), hair follicles prematurely enter the shedding phase. Shedding begins 2โ€“3 months later and can be dramatic. Typically self-limiting โ€” resolves in 6โ€“9 months once the trigger is removed.

3. Alopecia Areata

Autoimmune condition causing patchy, circular hair loss. Can progress to total scalp loss (alopecia totalis) or total body hair loss (alopecia universalis). Treatment options include topical/injectable corticosteroids and the newer JAK inhibitors (baricitinib, ritlecitinib โ€” highly effective, now NICE-approved in UK).

Evidence-Based Treatments

TreatmentTypeEffectivenessAvailability
Minoxidil (2% / 5%)Pattern hair lossStops progression in 90%; regrowth in 40โ€“60%OTC (Regaine)
Finasteride 1mgMale pattern onlyStops progression in 83%; regrowth in 66%Prescription
Oral minoxidil (low dose)All typesEmerging evidence โ€” effective and well-toleratedPrescription
Platelet-rich plasmaPattern + areataModerate evidencePrivate clinic
Correct nutritional deficienciesNutritional causesHighly effective if deficiency is the causeVia GP blood tests
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Frequently Asked Questions

How much hair loss is normal?โ–ผ
Losing 50โ€“100 hairs per day is completely normal โ€” scalp hair naturally cycles through growth, rest, and shedding phases. Concern is warranted when: you notice significantly increased shedding (handfuls in the shower, on pillows), visible thinning at the part line or temples, bald patches, or shedding accompanied by scalp symptoms (itching, burning, scaling). Photography of the part line monthly is a useful monitoring tool.
Does nutrition affect hair loss?โ–ผ
Yes โ€” nutritional deficiencies are a significant, often overlooked cause of hair thinning. The most important: iron deficiency (ferritin below 30 ฮผg/L is associated with hair loss โ€” a lower threshold than for anaemia), vitamin D deficiency, zinc deficiency, and protein inadequacy. A full blood count including ferritin, vitamin D, zinc, and thyroid function should be requested before assuming pattern hair loss.
Can stress cause hair loss?โ–ผ
Yes โ€” telogen effluvium. Significant physiological or psychological stress (surgery, illness, bereavement, pregnancy, extreme dieting) can push 30โ€“70% of hair follicles into the shedding phase simultaneously. The shedding typically appears 2โ€“3 months after the stressful event and resolves within 6โ€“9 months once the trigger is resolved. Chronic ongoing stress can cause persistent telogen effluvium.

Related Health Guides

โš•๏ธ Medical Disclaimer: For informational purposes only. Not a substitute for professional medical advice.
PS
Dr. Priya Sharma, MD
WellCalc Medical Contributor
All articles reviewed by qualified healthcare professionals following NHS, AHA, and WHO guidelines.