Anagen Effluvium & Telogen Effluvium


Excessive shedding of scalp hair. There are two significant forms of effluvium (Anagen and Telogen)


Much of the human skin possesses follicles engaged in hair-shaft production – except at the following locations: palms, soles, lips, eyelids, backs of distal phalanges and parts of the external genitalia. Most productive hair follicles create hair-shafts throughout healthy life. Some follicles may intermittently produce vellus or terminal hair shafts.

The repetitive four-phase ‘hair cycle’

Healthy hair follicles undergo cyclical degeneration with hair shaft eviction, usually followed by folliculo-re-genesis with a new immature hair-shaft within approx. 4-6 months..
The four specific phases are termed: Anagen, Catagen, Telogen and Exogen:

The following details apply to the majority who are in good health.
Pregnancy  can and often will initiate temporary changes to the hair cycle. 

The Anagen (growth) Phase – due to cell mitosis within the dermal papillae. Rates vary with ethnicity and body location but usually fall between  0.020cm – 0.040cm per day. The Anagen period is variable and unless interrupted by health issues or pregnancy has been known to provide ceaseless hair shaft production for periods of up to 10 years or more – this governs the ultimate length they can attain.  Unless interrupted approx. 80% of hair follicles will be in the Anagen phase at any given time.

The Catagen Phase (mitosis ceases, the follicle commences a shut down).

All hair follicles enter periods of degeneration throughout the persons life. Approx. 3% of healthy follicles will be entering a shutting down phase (Catagen) at any given time. During this period the epithelial sheath  shrinks to form a minute ‘club root’ attached to the hair shaft’s proximal extreme. The hairshaft is thus prepared for eviction. The Catogen phase lasts approximately 10-20 days.

The Telogen Phase (follicle resting phase in which hair shafts can commence their evacuation).

Approximately 12 – 17% of hair follicles are in the amitotic or resting (Telogen) phase at any given time. During this the prepared hair shafts vacate their scalp host follicles freely. This resting phase lasts for up to 100 days.  Follicles producing eyebrows, eyelashes, and other body hair may take differing periods of time. Following the telogen phase the follicles return to anagen which assist in the actual evacuation of the shaft (Exogen).

Exogen – the actual evacuation of the hair-shaft which often accompanies the new Anagen phase.

The average scalp has 84000 – 145000 hair follicles. In healthy persons at any given time, approximately
80% of scalp follicles are in the anagen phase which may last for up to 10 + years, with approx.17% in the telogen phase which lasts for approximately 100 days. 40-130 hair shafts vacate their follicle per day.
In disease / distress / pregnancy the anagen / telogen ratios are subject to dramatic change.

The author has observed patients losing all but the shortest hairs within 2-4 weeks of the onset of either effluvium.

Anagen Effluvium

Anagen Effluvium: a significant loss of hairshafts in their anagen phase. The onset may be rapid (e.g. Within 2-4 weeks of the cause). Major hair loss may result in extreme cases. Hair usually returns spontaneously.


  • Chemotherapy drugs (anti mitotic agents)
  • Radiotherapy
  • Malnutrition
  • Seborrhoeic dermatitis and other localised dermatoses.
  • Oral contraceptives
  • Vitamin A poisoning
  • Iron deficiency
  • Chronic infections
  • Some Drugs

Telogen Effluvium

Telogen Effluvium was first described in 1961. It relates to a specific form of diffuse hair loss.

Telogen Effluvium – eviction of hairshafts from follicles which have prematurely entered their resting phase. This can produce excessive hair losses, and may be thus explained: 

  1. Hair follicles prematurely terminate the anagen (mitosis) phase. 
  2. The Catogen phase of the hair cycle is omitted.
  3. Hair follicles prematurely enter the Telogen (amitotic or resting phase).
  4. Hairshafts are lost in great numbers.
  5. Hair follicles return to Anagen and new hairshaft production ensues.

Hair losses in TE usually present within 6-12 weeks following stresses and other triggering factors. In some patients, the hair fall rate may be sufficient to reduce a densely populated scalp to 1-2cm stubble within weeks. Lost hair usually re grows spontaneously.


  • Pyrexia (fever) in particular a body temperature of 102.5 C.
  • Childbirth (rarely)
  • Severe infection (especially toxaemia)
  • Major surgery
  • Protein deficiency due to unsupervised crash diets.
  • Drugs including beta blockers, antidepressants.
  • Severe psychological stress

What can you do to help?

A reputable trichologist may be consulted. Is there a Society Registered Trichologist near you? (see HAIR CONSULTANTS)

© Prof. B Stevens FTTS – Contact the author

NB  See also Hair loss following fever