Telogen effluvium is the second most common form of hair loss seen in clinical practice. Characterised by sudden, diffuse shedding — often dramatically more than usual — it is typically triggered by a physiological stressor and is, in most cases, fully reversible.
What Is Telogen Effluvium?
The normal hair cycle consists of a growth phase (anagen, lasting 2–6 years), a transitional phase (catagen), and a resting phase (telogen, lasting approximately 3 months) before the hair sheds. In a healthy scalp, approximately 10–15% of hairs are in telogen at any given time, resulting in normal daily shedding of 50–100 hairs.
In telogen effluvium, a physiological shock triggers a mass shift of follicles from anagen into telogen. This results in synchronised shedding — dramatically increased hair loss — approximately 2–3 months after the triggering event.
Common Triggers
Physical stress: Major surgery, serious illness, significant blood loss, or high fever can trigger telogen effluvium.
Hormonal changes: Post-partum hair loss (one of the most common forms) occurs 2–3 months after childbirth as the hormonal changes of pregnancy resolve and follicles that were sustained in anagen begin to shed. Stopping oral contraceptives can trigger a similar response.
Psychological stress: Severe emotional stress is a recognised trigger, though the relationship is more complex and less immediate than often assumed.
Nutritional deficiency: Low iron/ferritin, zinc deficiency, severe protein restriction, and crash dieting are common triggers.
Medications: Some medications — including anticoagulants, retinoids, and antithyroid drugs — can trigger telogen effluvium.
Thyroid disorders: Both hypo- and hyperthyroidism can cause telogen effluvium.
How Long Does It Last?
Acute telogen effluvium — where the trigger is identified and resolved — typically self-resolves within 3–6 months of trigger resolution. The total duration from trigger to full recovery is usually 6–12 months.
Chronic telogen effluvium (lasting more than 6 months) is less common and may indicate an ongoing trigger, nutritional deficiency, or co-existing condition requiring investigation.
Diagnosis
Diagnosis is typically clinical. A hair pull test — gently pulling 50–60 hairs from different scalp regions — assesses the proportion in telogen phase. Trichoscopy and blood tests (thyroid function, full blood count, ferritin, B12, vitamin D, zinc) help identify underlying causes.
Treatment
Treatment focuses on identifying and addressing the underlying trigger:
- Correct nutritional deficiencies (iron/ferritin is the most important)
- Treat underlying thyroid disease
- Manage stress where possible
- Minoxidil can be used to support recovery
Is Hair Transplant Appropriate?
No. Telogen effluvium causes diffuse, reversible shedding. Transplanting into a scalp undergoing active telogen effluvium produces poor results. Hair transplant is only considered for residual permanent loss after full recovery — which is rare in pure telogen effluvium without co-existing androgenetic alopecia.
Experiencing sudden increased shedding? Our team can help assess whether this is telogen effluvium or another cause — and advise on the most appropriate management.