The Hair Cycle and Diffuse Hair Loss


All Hair follicles grow in cycles. Each cycle consists of a long growing phase - Anagen, a short transitional phase – Catagen, and a short resting phase - Telogen. At the end of the Telogen resting phase, the hair falls out and a new Anagen hair starts growing in the follicle beginning the hair cycle again.


  • Anagen is the active growth phase of the hair follicles. In the Anagen phase, the cells in the root of the hair are dividing rapidly, adding to the hair shaft.
  • In a normal Anagen phase the hair grows about 1 cm every month. Anagen phase lasts from 2–8 years. The amount of time the hair follicle stays in the Anagen phase is genetically determined.
  • The longer the length you can grow your hair indicates a longer Anagen phase of 5 to 8 years. If you have never been able to grow long hair, you have a short Anagen phase of 2-4 years.
  • Normally up to 90% of the hair follicles on the scalp are in Anagen phase.
  • Under a microscope, Anagen hairs have a straight, well defined pigmented bulb and may be encompassed by the inner root sheath.
  • At the end of the Anagen phase an unknown signal causes the follicle to go into the Catagen phase.
  • Anagen Effluvium is a disruption of the growing phase that causes abnormal loss of anagen hairs.


  • Catagen is the short transition phase that occurs at the end of the Anagen phase.
  • Catagen signals the end of the active growth of a hair.
  • Catagen phase lasts for about 2–3 weeks. Normally 1-2% of hair follicles are in the Catagen phase.
  • Under a microscope, Catagen hairs have pointed, frayed looking bulb with a drooped root sheath if present, and no pigment activity.


  • Telogen phase is the resting/falling phase of the hair follicle and lasts for 2-3 months.
  • A Telogen hair is the final product of a hair follicle cycle, and is a dead, fully keratinized hair. 
  • 10-14% of hair follicles are in the Telogen phase. Normally 70-160 hairs reach the end of their resting phase each day and fall out.
  • Under a microscope, Telogen hairs have a club like bulb with the root sheath leaving a thin tail like projection from the base of the bulb, and no pigment activity.
  • Telogen Effluvium is clinical hair loss, when more than 160 hairs fall per day.


Diffuse Hair Loss (Diffuse Un-patterned Alopecia) is a loss of hair or generalized hair thinning that affects the entire scalp and is a common type of hair loss in both females and males of all ages. Diffuse Hair Loss is not a patchy type of hair loss nor is it hair loss in localized areas or typical patterns associated with hereditary male and female pattern hair loss and Alopecia Areata.

With Diffuse Hair Loss, much of the hair remains, but the diameter of the hair shaft is smaller than normal hair 'Diffuse Damaged', or the hair follicle is left empty until the hair cycle resumes. It is a sign that the normal hair cycle has been disturbed which results in the premature loss of Anagen (growing) hairs and a higher count of Telogen (falling) hairs lost on a daily basis. Total hair loss or complete baldness will never result from diffuse hair loss alone. 


Diffuse hair loss is your body's response to changes and can be caused by a variety of conditions.

Diffuse Hair Loss triggers can include but are not limited to:

  • A wide variety of physiologic and emotional stresses
  • Nutritional deficiencies
  • Endocrine imbalances
  • Shock
  • High fever
  • Operations
  • Stopping and starting certain medications
  • Food poisoning
  • Or having a baby, for example.

Loss of Telogen-phase hairs is the most common type of diffuse hair loss. Hair loss during the Anagen phase is usually caused by chemotherapy or radiation therapy. Loose Anagen Syndrome is an increasingly common type of diffuse hair loss with the premature loss of the Anagen (growing) hairs.

The cause of Diffuse Hair Loss triggers Anagen (growing) hairs to prematurely pass to the Catagen (resting) and then Telogen (falling) hair cycle stages. The scalp hairs effected by Diffuse Hair Loss will remain are in these stages for 2-3 months before you see the effect and notice hair falling from the scalp. Diffuse Hair Loss begins 2 to 3 months AFTER whatever triggered it. The amount of hair loss depends on the length and severity of the trigger and your individual sensitivity. Diffuse Hair Loss that occurs gradually and continues for OVER 3 months indicates an underlying 'health' problem that will require correction of the health problem for the hair loss to stop. Medical intervention may be required for this longer term diffuse hair loss.

If left unchecked, you may find yourself with diffuse damaged hairs replacing your normal growing hairs. Diffuse damaged hairs are mostly wiry, fine and frizzy. These diffuse damaged hairs are also very weak and will break easily during simple hair styling practises. Diffuse damaged hairs will not hold colour resulting in poor colour retention, colour fade and hard to style hair. Popular straightening and de-frizzing treatments will not fix diffuse damaged hairs, and will most likely break them adding to the hair loss.


Hair Breakage:

Sometimes what seems to be diffuse hair loss is actually hair breakage.

Microscopic and physical examination of hair bulbs and shafts can assist diagnosis of hair breakage from hair shaft defects and disturbances such as:
  • Protein Deficiency - poor diet or digestion can result in structural changes in the hair shaft. It only takes 15 days for a hair bulb to be impacted by a low protein diet as hair is 97% protein.
  • Blood Sugar Fluctuations - associated with diabetes commonly shows in the hair shaft as a disturbance.
  • Monilethrix - inherited hair shaft disorder characterized by a beaded appearance of the hair due to periodic thinning of the shaft. Typically results in hair fragility.
  • Trichorrhexis Nodosa - a defect in the hair shaft characterized by thickening or weak points (nodes) that cause the hair to break off easily.
The breakage contributes to the appearance of hair loss, lack of growth, and damaged-looking hair. Also often appears on hair with split ends.

The result of all hair shaft disturbances is narrowing or swelling of the hair shaft leaving a weakened area on the hair strand which will be easily broken with simple daily hairstyling. Over processing of the hair from chemicals such as straightening, bleaching and tinting can cause breakage of normal healthy hair, so imagine what they will do to a defective hair shaft!

Please contact Absolique Hair Health Clinic to recieve your Correct Diagnosis with a Hair Health and Scalp Check.