Hair grows from follicles in the skin. Scalp hair normally cycles through a long growth phase, called anagen, followed by a shorter resting and shedding phase, called telogen.
In normal circumstances, most scalp hairs are growing, while only a small proportion are resting or shedding at any one time.
Telogen Effluvium (TE) is a sudden, diffuse increase in hair shedding which can occur when a physical, metabolic, hormonal, nutritional or emotional stress causes many follicles to leave the growth phase early and enter the shedding phase simultaneously.
The shedding commonly begins one to four months after the trigger, most often around two to three months later. It is usually temporary, although the amount of hair shed can be very distressing.
Common triggers:
- Acute illness – especially fever, vomiting, diarrhoea or infection.
- Severe allergic or chemical reactions – including reactions to colour tints, perming solutions, topical treatments or toxic chemical exposure.
- Major stress or shock – including bereavement, relationship breakdown, workplace or financial crisis, or prolonged distress.
- Surgery, dental procedures or blood loss – particularly where complications occur.
- Medication changes: starting or stopping hormonal therapy, thyroid medication, anti-androgens, Minoxidil, some mood-stabilising or anti-depressant medicines (1), and anabolic steroids.
- Iron infusions, chemotherapy, dialysis or strong intravenous medicines which may act as a physiological stress in susceptible people.
- Rapid weight loss, crash dieting or major dietary change – especially when nutrient intake becomes inadequate.
- Post-partum hormonal changes: miscarriage or pregnancy termination. Post-partum shedding often begins about 8–10 weeks after childbirth and may be influenced by breastfeeding, sleep deprivation and mother’s nutritional status.
TE at a glance:
TE causes an abrupt onset, excessive diffuse shedding from the entire scalp; other facial hair is not affected. The practical definition of excessive shedding is ‘more hair than the individual would normally lose’.
In most cases, TE is temporary (2) and self-correcting once the trigger has passed and the body’s nutritional, hormonal and metabolic support improves.
Management
A careful history helps identify the likely trigger and confirm whether the timing and shedding pattern fit TE. Blood pathology may be useful to assess iron studies, zinc, vitamin D, iodine, B12, thyroid function and other relevant markers.
Reassurance is important: recovery of density is usually expected, but it can take time. Treatment should focus on correcting the underlying trigger, improving nutritional and metabolic support, and avoiding unnecessary chemical or styling trauma.
Where appropriate, supportive topical treatments and low-level laser/light therapy may be considered as part of a broader management plan.
- Hair loss associated with anti-depressant medication can be difficult to separate from the effects of the mood disturbance itself. Never cease prescribed anti-depressant medication without consulting your doctor.
- Persistent shedding over many months should be investigated rather than simply labelled ‘chronic Telogen Effluvium’.
Copyright Anthony Pearce 2009 (revised June 2026)