hair-loss
What Causes Hair Loss?
Last reviewed: May 2026 · Haute MD Editorial Team
Hair loss has many causes — the most common is androgenetic alopecia (male and female pattern hair loss), which is genetic and affects up to 50% of men by age 50 and 40% of women by menopause. Other frequent causes include telogen effluvium (stress- or illness-triggered shedding), hormonal changes (thyroid disorders, postpartum shifts, PCOS), nutritional deficiencies (iron, vitamin D, biotin), and certain medications (blood thinners, antidepressants, chemotherapy). Identifying the cause is essential before choosing any treatment.
Why cause identification matters before treatment
The treatment for genetic pattern hair loss (minoxidil, finasteride, PRP) is completely different from the treatment for iron-deficiency hair loss (iron supplementation) or thyroid-related loss (thyroid management). Treating the wrong cause wastes time and money and delays recovery. A board-certified dermatologist can identify the cause through scalp examination, pull test, and blood panels within a single visit.
The most common causes of hair loss
Androgenetic alopecia is the most common cause in both men and women — driven by DHT sensitivity in hair follicles and strongly influenced by genetics. Telogen effluvium is the second most common — a diffuse shedding that occurs 2-3 months after a triggering event such as illness, surgery, extreme stress, crash dieting, or childbirth. Alopecia areata is an autoimmune condition causing patchy loss. Traction alopecia results from tight hairstyles. Scalp conditions (seborrheic dermatitis, psoriasis, ringworm) can also cause localized loss.
When to see a dermatologist
See a board-certified dermatologist when hair loss is diffuse (all over) rather than patterned; hair loss appears suddenly rather than gradually; you notice scalp changes (redness, scaling, inflammation); you have other symptoms (fatigue, weight changes, menstrual irregularity); or over-the-counter treatments have not helped after 4-6 months. Early intervention preserves more follicles — delay reduces treatment options.
Frequently Asked Questions
Is hair loss reversible?
Depends on the cause. Telogen effluvium almost always reverses once the trigger is resolved. Androgenetic alopecia can be slowed and partially reversed with treatment but follicles lost for years may not regrow. Alopecia areata can resolve spontaneously or with treatment. Traction alopecia reverses early but becomes permanent if the follicle is scarred.
What blood tests check for hair loss causes?
A dermatologist typically orders complete blood count (CBC), ferritin (iron stores), thyroid panel (TSH, free T4), vitamin D, zinc, and hormones (testosterone, DHEA, prolactin in women). These identify the treatable medical causes of hair loss.
Does stress cause permanent hair loss?
Stress-triggered telogen effluvium causes significant shedding 2-3 months after the stressor but is almost always temporary. Hair typically regrows fully within 6-12 months once the stressor resolves. Chronic, unrelenting stress can extend the shedding period but rarely causes permanent loss in otherwise healthy follicles.
At what age should I see a doctor about hair loss?
At any age — hair loss at 20 warrants just as much evaluation as hair loss at 50. Earlier evaluation and treatment preserve more follicles and more options. Do not wait until loss is visible to others before seeking evaluation.
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Dr. Daniel Scott Karempelis
Dermatologist
Dermatology · Atlanta, Georgia, GA
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Dermatology · Aventura, FL
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Dermatology · Bryn Mawr, PA
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