Hormone Journal

Telogen effluvium

Pronounced: TEL-oh-jen ef-FLOO-vee-um

Also known as: TE, stress-related hair shedding

Medically reviewed by Hormone Journal Editorial Team · Last reviewed 2026-05-22

Telogen effluvium is a common, usually temporary form of diffuse hair shedding triggered by physical or emotional stress, causing follicles to prematurely enter the resting phase and shed 2–3 months later.

What it is

Telogen effluvium (TE), also called stress-related hair shedding, is one of the most common causes of hair loss in women, characterized by sudden diffuse shedding across the entire scalp rather than patchy or patterned loss. In a healthy scalp, roughly 85–90% of follicles are in the active growth phase (anagen) and 10–15% are in the resting phase (telogen) at any given time. In TE, a significant stressor forces a large proportion of anagen follicles to shift prematurely into telogen simultaneously. When those follicles shed approximately 100 days later, the result is a noticeable, often alarming increase in daily hair loss. The condition is non-scarring — follicles remain intact — and in most acute cases resolves fully within 3 to 6 months of removing the trigger. When shedding persists beyond 6 months, the condition is classified as chronic telogen effluvium, which requires a more thorough investigation for an ongoing or unrecognized cause.

For Canadian patients, TE is frequently encountered in primary care and is often undertreated because clinicians and patients alike assume it will self-resolve. When a treatable cause such as iron deficiency or thyroid dysfunction is present, identifying and addressing it meaningfully shortens recovery.

Causes and mechanism

Virtually any significant physical or emotional stressor can trigger TE, with hair loss appearing 2 to 3 months after the event — the lag time reflects the length of the telogen phase itself.

Hormonal causes account for a large share of cases:

Hormonal triggerMechanismTypical timing
Postpartum (most common form)Estrogen fall after delivery releases follicles held in anagenShedding peaks 2–4 months postpartum
Hypothyroidism or hyperthyroidismThyroid hormones regulate follicle cycling directlyGradual onset; may persist until TSH normalizes
Perimenopause / menopauseDeclining estrogen reduces growth-promoting effect on folliclesInsidious onset over months to years
Starting or stopping hormonal contraceptivesEstrogen withdrawal or shift in androgen balance2–3 months after the change

Non-hormonal causes include iron deficiency anemia (one of the most commonly missed triggers, particularly in women of reproductive age with heavy periods), major illness or surgery, significant weight loss or crash dieting, nutritional deficiencies (protein, vitamin D, B12, zinc), chronic psychological stress, COVID-19 and other viral infections, and certain medications including anticoagulants, antithyroid drugs, retinoids, and beta-blockers.

Symptoms and diagnosis

The hallmark is diffuse shedding across the whole scalp — not a receding hairline or discrete bald patches. Patients typically notice more hair in the shower drain, on pillows, and when brushing. The hair part may appear wider and the scalp more visible overall, but complete baldness is rare because follicles remain viable.

Diagnosis rests on four steps:

  1. Clinical history — identifying a stressor 2 to 3 months before shedding onset is often the most informative step.
  2. Hair pull test — gently pulling 40 to 60 hairs from multiple scalp areas; extracting more than 6 telogen (club-shaped root) hairs confirms active TE.
  3. Trichoscopy — dermoscopic examination of the scalp and hair shafts to rule out other alopecia types.
  4. Blood work — essential for identifying reversible causes. In Canada, LifeLabs and Dynacare both process the relevant panel: full blood count, ferritin (must be specifically requested — a normal hemoglobin does not exclude iron deficiency), TSH with reflex T3/T4, vitamin D, B12, zinc, and a hormonal panel (androgens, FSH, estradiol) if PCOS or a perimenopausal transition is suspected.

Treatment options

The most effective treatment is identifying and correcting the underlying trigger.

Correcting reversible causes:

  • Iron deficiency: oral iron supplementation until ferritin is restored to levels above 70–80 mcg/L, which research suggests is the threshold for optimal hair follicle cycling — well above the standard lab reference range of 12–15 mcg/L.
  • Thyroid dysfunction: levothyroxine for hypothyroidism; antithyroid therapy for hyperthyroidism. Hair recovery typically follows TSH normalization over several months.
  • Nutritional deficiencies: restoring adequate dietary protein, vitamin D, B12, and zinc through diet and supplementation as indicated.
  • Stress: targeted stress management for stress-related TE, though evidence for specific interventions remains limited.

Supporting regrowth:

  • Minoxidil (topical 2–5% or low-dose oral) promotes follicle re-entry into anagen and can shorten recovery, particularly in chronic TE or when TE is superimposed on androgenetic alopecia. In Canada, topical minoxidil is available over the counter; low-dose oral minoxidil requires a prescription and is not yet covered under most provincial formularies, though it can be accessed through telehealth platforms such as Felix, Maple, Cleo, Phoenix, or others.
  • Postpartum TE specifically: reassurance is the primary intervention. The condition is physiological and self-limiting, with hair density typically returning to baseline by 12 months postpartum without specific treatment.

When to see a clinician in Canada

See a family physician or dermatologist if:

  • Diffuse shedding is causing significant distress and began 2 to 3 months after a known stressor, illness, or hormonal change.
  • Shedding has not improved after 3 to 4 months, or has no obvious cause — this warrants blood work to rule out iron deficiency, thyroid dysfunction, and nutritional gaps.
  • Hair loss is accompanied by fatigue, cold intolerance, irregular periods, or changes in skin and nails, which may point to a systemic hormonal or nutritional driver.
  • Shedding has persisted beyond 6 months (chronic TE), which requires a more thorough workup.

Most provincial health plans cover the diagnostic blood work and physician visits needed to investigate TE. Dermatology referrals may involve wait times; telehealth platforms can expedite initial assessment and prescription access where appropriate.

Limitations and open questions

Research is still emerging on the precise ferritin threshold needed to support hair regrowth — the commonly cited target of 70–80 mcg/L comes from observational data and expert consensus rather than randomized trials. The optimal duration and dose of oral minoxidil for TE specifically has not been established in large controlled studies. Health Canada has not issued specific guidance on TE management, and no Canadian clinical practice guideline currently addresses it as a standalone condition. The relationship between chronic psychological stress and TE is biologically plausible but difficult to quantify, and evidence for stress-reduction interventions as a direct treatment for TE remains limited. For patients whose shedding does not resolve after addressing identified triggers, the distinction between chronic TE and early androgenetic alopecia can be clinically difficult and may require specialist evaluation.

FAQs

Is telogen effluvium permanent?

In the majority of cases, telogen effluvium is temporary and fully reversible. Once the triggering cause is resolved, follicles gradually re-enter the anagen phase and hair density recovers over 3 to 6 months. Chronic telogen effluvium — defined as shedding lasting more than 6 months — does occur when an ongoing or unrecognized trigger persists, but even in those cases, identifying and treating the cause typically leads to meaningful improvement. Complete, permanent hair loss from TE alone is rare because the follicles themselves remain intact throughout.

How much hair loss is normal, and how do I know if mine is excessive?

Shedding 50 to 100 hairs per day is considered normal as part of the natural hair cycle. In telogen effluvium, daily shedding can temporarily rise to 200 to 400 or more hairs per day. The most practical sign that shedding is abnormal is noticing a significant increase in hair accumulating in the shower drain, on pillows, or when brushing — particularly if this change appeared suddenly over a few weeks. Because follicles remain intact in TE, this level of shedding rarely leads to complete baldness, though diffuse thinning and a wider-looking part are common.

Why does hair fall out after pregnancy?

During pregnancy, elevated estrogen prolongs the anagen (growth) phase of the hair cycle, so fewer follicles than usual enter the resting phase — many women notice their hair feels thicker as a result. After delivery, estrogen levels fall rapidly, releasing the large cohort of follicles that had been held in anagen. Two to four months later, those follicles shed simultaneously, producing the characteristic diffuse postpartum hair loss. This is entirely physiological and self-limiting; hair density typically returns to pre-pregnancy baseline by 12 months postpartum without specific treatment.

Can iron deficiency cause hair loss, and will a standard blood test catch it?

Yes — iron deficiency is one of the most commonly missed causes of telogen effluvium, particularly in Canadian women of reproductive age with heavy menstrual periods. Ferritin, the body's iron storage protein, is required for normal hair follicle cycling; studies suggest ferritin levels below 30–40 mcg/L are associated with increased shedding, and optimal hair regrowth may require levels above 70–80 mcg/L. A standard complete blood count can miss iron deficiency entirely if hemoglobin is still within the normal range, so ferritin must be specifically requested. Both LifeLabs and Dynacare process ferritin as a standalone test, and it is covered under provincial health plans when ordered by a physician.

How is telogen effluvium different from androgenetic alopecia (female-pattern hair loss)?

Telogen effluvium causes diffuse shedding across the whole scalp and is typically triggered by a specific event, with shedding peaking 2 to 3 months later and then gradually resolving once the cause is addressed. Androgenetic alopecia (female-pattern hair loss) is a progressive, genetically influenced condition driven by androgen sensitivity in follicles, producing a characteristic pattern of thinning at the crown and widening of the central part rather than uniform diffuse loss. The two conditions can coexist — TE can unmask or accelerate underlying androgenetic alopecia — which is one reason shedding that does not fully resolve after treating an identified trigger warrants specialist evaluation. A dermatologist or trichologist can use trichoscopy and clinical history to distinguish between them.

Sources

All glossary termsUpdated 2026-05-22