Diffuse hair loss
Diffuse hair loss


Telogen effluvium is a common type of hair loss where there is excessive shedding of hair, slow hair growth or general hair thinning.  Telogen effluvium may self-correct without any intervention within a few months.  Chronic telogen effluvium is where the condition persists for more than 6 months.

Chronic telogen effluvium does not cause complete hair loss and the hair follicle unit is not damaged. 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.  If the telogen to anagen ratio can be restored shedding will gradually reduce and normal hair density will be restored.  When the anagen to telogen ratio is restored, it can take 12-18 months for hair to return to maximum thickness.

Telogen effluvium is a reactive type of hair loss that can be complicated by non-genetic inheritance. Other factors that can contribute to the condition includes hormonal changes, gut bacteria dysbiosis, high blood sugar, abnormal cholesterol profile, iron deficiency anemia, impaired thyroid function, high cortisol, childbirth, vitamin deficiencies, mineral deficiencies and medication.

Telogen signs and symptoms


Telogen effluvium is a reactive type of hair loss that can run in the family due to non-genetic inheritance.  Non-genetic inheritance involves a diverse range of mechanisms which act together or independently to alter the expression and transcription of genes.

Non-genetic inheritance results in DNA modifications such as: DNA methylation, histone modifications and changes in small non-coding RNAs.  These modifications act to repress gene transcription.  For example, non-genetic inheritance can reduce keratin manufacture in the hair follicle leading to slow, thin hair.

Inheritable factors that increase the chances developing telogen effluvium mainly involve parental nutrition and health status.  For example, parents with even mild nutritional deficiencies (iron, zinc, protein), stressful prenatal conditions, high fat or sugar diets, sedentary lifestyles, high alcohol consumption or high levels of visceral fat (invisible fat between organs) can transmit altered DNA methylation states to their offspring.


Hair grows in three distinct cycles: anagen, catagen and telogen.  The normal hair growth cycle is altered in 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.

With an increased number of hairs in telogen phase, hair shedding will increase and appear not to grow any longer.  In telogen effluvium, 20-60% of hairs can be in the resting phase, ready to be shed from the scalp.  To regrow hair, the anagen / telogen balance must be restored.


Telogen effluvium is diagnosed during a clinical, when a hair pull test is positive or by trichogram investigation.  If hair loss is focused in any 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 and confirm a positive 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.

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 to produce 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 steroidogenesis, 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 not 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.

Glycated haemoglobin (HbA1c) | This test shows you your average blood sugar level for the previous 2 – 3 months.  This test is normally used for the detection of type II diabetes but can also be useful when investigating telogen effluvium.  If you have a high/normal HbA1c result (above 4.4%), this could indicate your blood sugar levels may be contributing to your hair loss.  A high HbA1c level can also be due to anemia or iron deficiency.


There are many common triggers of reactive hair loss:

  1. Family history of hair loss | Non-genetic inheritance plays a role in telogen effluvium.  If you have a family history of thinning hair, it is useful to identify other common contributing factors to hair loss that also run in the family such as anaemia, cardiovascular disease or diabetes.
  2. Hormonal changes | Changes in levels of androgens and estrogens can lead to a range of frustrating and aesthetically displeasing health issues such as adult acne and abdominal weight gain.  If your hormones are out of balance, you may also notice excess hair on your chin and on your stomach due to higher levels of DHT.  Increased levels of DHT are known to contribute to female pattern hair loss (androgenic hair loss), DHT can also contribute to the reduced growth and increased shedding that is commonly seen in telogen effluvium when there is a mild increase in the DHT.
  3. High Cortisol | Cortisol is a catabolic hormone that prevents growth and promotes the breakdown of tissue and collagen to provide an immediate source of fuel for the body.  Cortisol levels are normally highest in the morning and drop after breakfast.  Never skip breakfast and focus on proteins, healthy fats and complex carbohydrates to keep blood sugar levels stable.  Calorie restriction or fasting will increase cortisol, so eat every few hours.  Coffee and caffeine containing beverages increase cortisol levels, so go for a decaffeinated flat white occasionally.
  4. Vitamin + mineral imbalance | One of the most common causes of hair loss is iron deficiency, iron is crucial for the production of proteins that make up the hair fibre and without it your hair will suffer.  Other important nutritional components that are essential for hair growth include B-complex vitamins, zinc and potassium.
  5. Some medical conditions | Some medical conditions such as hypothyroidism, hemochromatosis, Crohn’s, endometriosis and PCOS are major triggers of telogen effluvium.
  6. Prescription medication | Certain prescription and recreational drugs can lead to excess hair shedding.  If you are taking prescription medication such as antidepressants, immunosuppressants, cholesterol lowering medication or acne medication, talk to a medical professional about your hair loss concerns.  If you regularly take recreational drugs such as cocaine or marijuana, this can also impact hair loss.
  7. Recent childbirth | Due to hormonal changes, it is common to experience temporary shedding after childbirth.
  8. Gut bacteria dysbiosis | Bacterial dysbiosis can lead to chronic low-grade inflammation, this keeps cortisol levels high and reduces the production of growth hormone. Bacterial dysbiosis also lowers the uptake of essential nutritional components of the diet.
  9. High blood sugar | High blood sugar leads to a narrowing of blood vessels in the scalp.  This can lead to a reduced supply of blood and oxygen to the hair follicles and the surrounding extracellular matrix that houses the hair follicles.
Causes of telogen effluvium


Most types of hair loss can be reversed if the condition is investigated, and the trigger is identified and remedied or removed.  It is important to note that in most cases telogen effluvium is a short-term condition that self-corrects with no intervention.  If shedding, thinning or slow growth continues for more than 6 months, you should seek advice.  Depending on the severity and duration of hair loss you can seek advice from your doctor, a trichologist or a dermatologist.