Dermatology
What Causes Hair Loss?
Last reviewed: May 2026 · Haute MD Editorial Team
Hair loss (alopecia) is caused by a wide range of factors. The most common cause is androgenetic alopecia — genetically programmed hair follicle sensitivity to dihydrotestosterone (DHT) — which affects both men and women. Other causes include hormonal imbalances (thyroid disorders, postpartum hormonal shifts), nutritional deficiencies (iron, vitamin D, zinc, biotin), telogen effluvium (stress or illness-triggered shedding), autoimmune conditions (alopecia areata), medications, and inflammatory scalp conditions.
Types of hair loss
Androgenetic alopecia: genetic, progressive thinning following predictable patterns. Telogen effluvium: diffuse shedding triggered by stress, illness, surgery, or hormonal changes. Alopecia areata: autoimmune condition causing patchy or total hair loss. Traction alopecia: caused by tight hairstyles. Scarring alopecias: inflammatory conditions that permanently damage follicles.
When should you see a dermatologist for hair loss?
See a dermatologist if you are losing more than 100-150 hairs per day, if hair loss is sudden or patchy, if you notice scalp redness, scaling, or scarring, or if over-the-counter treatments such as minoxidil have not helped after 6 months.
How is hair loss treated?
Treatment depends on the cause. Androgenetic alopecia is treated with minoxidil (topical or oral), finasteride (for men), spironolactone (for women), PRP therapy, low-level laser therapy, and hair transplant surgery. Nutritional deficiencies are corrected with supplementation. Alopecia areata may respond to corticosteroid injections.
Frequently Asked Questions
Is hair loss permanent?
It depends on the cause. Androgenetic alopecia causes progressive, permanent loss without treatment. Telogen effluvium and nutritional deficiency-related shedding are typically reversible once the underlying cause is addressed.
Can stress cause hair loss?
Yes. Telogen effluvium, triggered by significant physical or emotional stress, causes widespread hair shedding typically 2-3 months after the stressful event. Most cases resolve on their own within 6 months.
At what age does hair loss start?
Androgenetic alopecia can begin as early as the late teens or early twenties in men, though it most commonly becomes noticeable in the 30s and 40s. In women, significant hair thinning often begins after menopause.
Does hair loss from COVID-19 grow back?
Post-COVID hair loss is typically telogen effluvium — a reactive shedding phase triggered by the illness — and usually regrows within 6-9 months without treatment.
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Dermatology · Atlanta, Georgia, GA
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Dermatology · Aventura, FL
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Dermatology · Bryn Mawr, PA
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