Telogen effluvium
Telogen effluvium


Telogen effluvium is a common type of temporary hair loss where there is excessive shedding of the hair for a defined period of time.  Telogen effluvium normally self-corrects within 6 months of onset without any intervention.  After the initial period of shedding hair may appear thin and lack volume, the patient may notice her ends are thin and sparse.

Normally around 10% of hairs are in the telogen stage, in telogen effluvium 20-60% of hairs can be in the resting phase ready to be shed from the scalp [1].


Telogen effluvium is common after childbirth, surgery, or a period of stress.  Other factors that can lead to this condition are abnormal cholesterol levelsiron deficiency, low thyroid function, low calorie diets or impaired liver function.

Low levels of zinc, vitamin D and potassium will also contribute the shortening of the anagen cycle and a larger number of hairs being shed from the scalp.  If the factor that caused the shedding is remedied, hair will regrow as normal.


The normal hair growth cycle is altered in cases telogen effluvium. Normally 90% of hairs will be in anagen phase (growth phase), in anagen the hair follicle is firmly anchored to the scalp.  In telogen effluvium more than 10% of hair will be in telogen phase (resting phase).

In telogen, the hair follicle has disconnected from the dermis and sits unanchored in the epidermis.  A hair fibre in telogen phase will not grow and is not firmly anchored, thus, these hairs will easily be pulled out during brushing or washing.

Hair cycle; growth and regression of the hair follicle


Telogen effluvium is a non-scarring type of hair loss which can reduce hair density by up to 60%.  Blood tests will show no evidence of inflammation but may show an abnormal cholesterol profile, low thyroid function or a nutritional deficiency.

In this case the anagen phase has shortened and the hair fibre continually goes into resting phase early resulting in a larger percentage of hairs in telogen phase. Sometimes shedding continues over month or years.  Chronic telogen effluvium does not cause complete hair loss and the hair follicle unit is not damaged.  If the telogen to anagen ration can be restored shedding will gradually reduce and normal hair density will be restored.  When the anagen to telogen ration is restored, it may take several months for hair to return to normal thickness.


Telogen effluvium is diagnosed when a clinical examination shows diffuse hair thinning, when a hair pull test is positive or by trichogram investigation.  If hair loss is focused in any particular area such as the temples or crown, other types of hair loss should be considered.  A hair pull test is a popular and simple method of diagnosing the condition.  A hair pull test is positive when more than 10% of hairs can be removed with a light tug.

Trichogram investigation can establish the exact percentage of club hairs to confirm the hair pull test.  For more severe cases of chronic telogen effluvium, a scalp biopsy can establish the ratio of terminal (mature) hair fibres and confirm the absence of inflammation or fibrosis around the hair follicle.

Diagnosing telogen effluvium


Blood tests can be used to identify common causes or contributors to telogen effluvium.

Thyroid function |Low thyroid function can contribute to slow growing hair that sheds excessively.  Thyroid hormone is necessary for the production of keratin protein within the hair matrix.

Zinc | Low levels of zinc are linked to a decrease in growth hormone and related growth factors.  Zinc is also required for steriodogensis, and the inhibition of dihydrotestosterone (DHT).

B Vitamins | These vitamins are crucial for hair growth and normal metabolic cell function.  Clinical trials prove links between low levels of B-complex vitamins are linked to hair loss.

Ferritin / Serum Iron / TIBC / Transferrin saturation | Iron deficiency contributes to hair loss and can be identified by serum ferritin, serum iron, and TIBC (total iron binding capacity).  Low ferritin levels are diagnostic marker of an iron deficiency but high levels do nor confirm low iron availability in the body.

Vitamin D | Hair loss is associated with low levels of vitamin D and other fat-soluble vitamins.  Vitamin D has emerged as the second most important nutrient (after iron) in healthy body functioning.  Scalp biopsies in balding heads have shown that affected follicles have an increased level of vitamin D receptors on the cell membrane.

Cholesterol |  Abnormal levels of cholesterol can contribute to hair loss.  Research shows that. Cholesterol homeostasis affects to hair follicle biology and normal formation of the hair matrix.


It is important to note that in a majority of cases telogen effluvium is a short-term condition that self-corrects with no intervention.  If shedding continues for more than 6 months or your hair does not return to its normal density within 12 months you may want to seek advice.  Speak to your doctor about hair loss diagnostic options and speak to a hair loss expert that can interpret blood tests for hair loss.

There are a number of treatment options available for telogen effluvium and often hair loss can be recovered in a number of months.  Remember to eat regularly, exercise, and check for common vitamin and mineral deficiencies that can contribute to the problem.


  1. Kligman, A.M., 1961. Pathologic dynamics of human hair loss: I. Telogen effluvium. Archives of dermatology, 83(2), pp.175-198.
  2. Palmer, M.A., Blakeborough, L., Harries, M. and Haslam, I.S., 2020. Cholesterol homeostasis: Links to hair follicle biology and hair disorders. Experimental dermatology, 29(3), pp.299-311.