Telogen Effluvium

How hair growth works

Each hair follicle cycles through phases:

• anagen (growth): 2 to 7 years; about 85% to 90% of hairs
• catagen (transition): about 2 weeks
• telogen (rest): about 3 months, then the hair falls out and a new one starts growing

It is normal to lose about 50 to 100 hairs a day. In telogen effluvium, a shock pushes many more hairs than usual into telogen at the same time. About 2 to 3 months later, they all shed together, often 300 or more hairs a day.

Causes and triggers

Physical stress

• high fever or serious infection, including COVID-19 and flu
• major surgery or general anesthesia
• serious illness, hospitalization or injury
• significant blood loss

Hormonal changes

• childbirth: postpartum shedding usually starts 2 to 4 months after delivery
• stopping hormonal contraception
• hypothyroidism or hyperthyroidism

Nutrition

• crash or very low-calorie diets, rapid weight loss, including after bariatric surgery
• iron deficiency
• low protein intake
• deficiencies of zinc, vitamin D or B12 (less clear evidence)

Medicines

• beta-blockers, anticoagulants, retinoids (including high-dose vitamin A), some antidepressants, anticonvulsants, lithium
• starting or stopping hormonal treatments

Emotional stress

• bereavement, divorce, job loss or other major life stress

Sometimes no trigger is found, particularly in chronic telogen effluvium.

Symptoms

• noticeably more hair falling out when washing, brushing or on the pillow
• hairs with a small white bulb at the root (telogen hairs)
• diffuse thinning all over, sometimes more noticeable at the temples
• no bald patches, scarring, redness or scaling
• hair that feels less full

Telogen effluvium vs other hair loss

Telogen effluvium can unmask underlying pattern hair loss. See also alopecia and trichotillomania.

Diagnosis

A doctor or dermatologist will:

• ask about events in the 2 to 4 months before shedding started
• examine the scalp, often with a dermatoscope
• perform a hair pull test: gently pulling about 60 hairs; more than 6 coming out suggests active shedding
• order blood tests: complete blood count, ferritin (iron stores), thyroid function, and sometimes vitamin D, zinc or hormones
• rarely, perform a scalp biopsy if the diagnosis is unclear

Treatment

• Treat the cause: correct iron deficiency, treat thyroid disease, review medicines with your doctor, eat enough protein and calories.
• Be patient: shedding usually stops within 3 to 6 months of the trigger resolving; visible regrowth takes another 6 to 12 months because hair grows about 1 cm (0.4 inches) a month.
• Gentle hair care: avoid tight hairstyles, harsh chemical treatments and excessive heat.
• Topical minoxidil may help regrowth in some people, particularly chronic telogen effluvium or when pattern hair loss coexists.
• Stress management if stress is the trigger.
• Avoid unproven supplements unless a deficiency is confirmed; excess vitamin A or selenium can worsen hair loss.

Outlook

Acute telogen effluvium resolves completely in most people, with hair regrowing over months. Chronic telogen effluvium, lasting more than 6 months, mainly affects women aged 30 to 60 and may fluctuate for years, but it does not cause baldness.

Frequently asked questions

What causes telogen effluvium?

It is triggered by a shock to the body or mind, such as high fever, COVID-19, childbirth, surgery, crash dieting, severe stress, iron deficiency, thyroid problems or certain medicines. Shedding begins about 2 to 3 months after the trigger.

How long does telogen effluvium last?

Acute telogen effluvium usually lasts up to 6 months. Shedding slows once the trigger resolves, and hair gradually regrows over the following 6 to 12 months. Chronic telogen effluvium can last longer than 6 months.

Will my hair grow back after telogen effluvium?

Yes. Telogen effluvium does not damage hair follicles, so hair grows back once the cause is corrected. Full return of volume can take a year or more because hair grows slowly.

Can stress cause hair loss?

Yes. Severe emotional or physical stress can trigger telogen effluvium, with heavy shedding starting a few months later. Stress can also worsen alopecia areata and trigger hair-pulling in some people.

Is postpartum hair loss telogen effluvium?

Yes. During pregnancy, high hormone levels keep hairs in the growth phase. After birth, many hairs enter the resting phase together and shed about 2 to 4 months later. It usually resolves by the baby's first birthday.