Telogen effluvium

Key takeaways

• It is a timing problem, not follicle damage. A trigger pushes many growing hairs into the resting phase at once, and they shed together a few months later. Triggers reviewed include drugs, physical illness, surgery, emotional stress and nutritional problems (Asghar 2020).
• Acute telogen effluvium usually resolves on its own. Shedding typically stops around 3 to 6 months after onset once the trigger is removed (Ohyama 2025).
• Chronic telogen effluvium may not be a distinct disease. A systematic review of 18 studies (1,628 cases, 97.5% female) found none had excluded all other causes and that every biopsy study showed a normal ratio of terminal to vellus hairs. It concluded many cases are early female pattern hair loss, a hidden trigger, or normal shedding noticed by an anxious person with long hair (Daunton 2023).
• Pattern loss often hides underneath. In 200 women with postpartum shedding, only 9.5% had telogen effluvium alone; 56% also had androgenetic alopecia and 28% had it together with traction alopecia (Galal 2024). See androgenetic alopecia.
• Blood tests are for finding a reason, not for treating numbers blindly. A 2026 meta-analysis found lower ferritin and vitamin D in people with telogen effluvium than in controls, with high heterogeneity (Ahmed 2026). A 2024 case-control study of 90 women with chronic telogen effluvium found no difference in haemoglobin, ferritin, B12, vitamin D or thyroid tests (Durusu Turkoglu 2024). See iron and ferritin and thyroid and hair.
• There is no proven drug treatment. The only prospective minoxidil data are an open-label, single-arm trial of 12 Japanese people using 5% lotion twice daily for 24 weeks, which reported more terminal hairs and less shedding but had no control group in a condition that heals by itself (Ohyama 2025).

What it is

At any moment most scalp hairs are growing and a minority are resting. In telogen effluvium a large share of follicles switch early into the resting phase, then shed about 2 to 3 months later (see hair growth cycle). Hair thins diffusely without bald patches.

Common triggers are fever or severe infection (including COVID-19), surgery, major weight loss or crash dieting, childbirth (postpartum hair loss), iron or other nutritional deficiency, thyroid disease and some drugs. Chemotherapy causes a different, faster pattern (anagen effluvium).

Diagnosis rests on a history that places the trigger 2 to 4 months earlier, a pull test, a close look at the scalp, and targeted blood tests such as iron studies and thyroid function. Hair wash tests, trichograms and biopsy exist for difficult cases (Asghar 2020).

What the studies show

See the key takeaways. In short: acute cases settle on their own, chronic cases are often something else, and treatment evidence is thin. Women told they have chronic telogen effluvium should be checked for early pattern loss, because treatment differs (Daunton 2023).

Hair type notes

• Long hair makes shedding highly visible in brushes and drains, and normal daily loss may be misread as telogen effluvium.
• Nearly all chronic cases in the literature are women.
• An inflamed, itchy or flaky scalp needs a separate diagnosis.

Myths and facts

• Stress does not make hair fall out the next day; shedding lags the trigger by 2 to 3 months.
• Heavy shedding does not mean you are going bald. Acute telogen effluvium is self-limiting, though pattern loss can coexist.
• Not everyone who sheds is deficient in something; most tested nutrients were normal in the 2024 case-control study.
• Biotin has no telogen effluvium evidence and can distort thyroid blood tests (see biotin).

Bottom line

Identify and address the trigger, avoid crash diets, and replace nutrients only where tests show a deficiency. See a clinician if shedding lasts beyond about 6 months or the hair visibly thins. Minoxidil is optional, off-label and unproven for this condition. Regrowth looks like short baby hairs at the temples for months. Discuss with a doctor.