The Life Cycle of the Hair Follicle

There are three stages that every hair follicle goes through:

- Anagen (a phase of active growth)

- Catagen (a transition phase between the anagen and telogen phase)

- Telogen (the natural phase of shedding)

At any one time, all three phases are occurring at any site on the body. A single follicle will go through the anagen phase followed by the catagen phase and then the telogen phase before returning to the anagen phase. 

What is Telogen Effluvium?

Normally 10% of a person's hair is in the telogen phase. Telogen effluvium occurs when there is a higher than average amount of hair shedding, 30% of more. Common triggers for this change in the usual telogen stage include childbirth, trauma, illness, bereavement, sudden weight loss, new medication or hormonal changes. In around a third of those affected, no cause can be found.

What does Telogen Effluvium look like?

Hair shedding occurs all over the scalp, resulting in a reduced volume of hair.

Is Telogen Effluvium permanent?

Telogen Effluvium usually resolves itself completely, as the normal length of the telogen phase is around 3 to 6 months after which period the hair begins to grow again (anagen phase). How long it takes for hair volume to return to normal will vary according to the length of hair.

Can Telogen Effluvium be treated?

There is normally no treatment required for Telogen Effluvium as the hair will start growing once the trigger is removed. Medication is not required. Telogen Efflvium can return if the underlying cause is not treated or if it recurs.

What is Anagen Effluvium?

Anagen Effluvium refers to the shedding that arises during the anagen (growth) stage of the hair cycle. The main causes of Anagen Effluvium are radiation, chemotherapy, infection, drugs and toxins.

What does Anagen Effluvium look like?

Sudden shedding of much of or all of the hair on the scalp and often from the entire body, including eyebrows, eyelashes and body hair.

Is Anagen Effluvium permanent?

In most cases the hair will eventually return once the underlying cause is treated/removed. Anagen Effluvium as a result of chemotherapy treatment will normally recover within 3-6 months of the treatment being stopped.

Further Reading

The British Association of Dermatologists (BAD) has produced Patient Information Leaflets for all types of skin conditions, including types of alopecia. The BAD Patient Information Leaflets provide details of treatment options available.