To properly understand hair loss, you must first understand the biology of hair and how this intricate system works together to produce new, healthy, and long living hair. At any given time, a random number of hairs will be in various stages of growth. The three are stages are: catagen, telogen, and anagen.


Catagen: The catagen phase is a transitional stage and 3% of all hairs are in this phase at any time. This phase lasts for about 2-3 weeks. During this time growth stops and the outer root sheath shrinks and attaches to the root of the hair. This is the formation of what is known as a club hair.

Telogen: Telogen is the resting phase and accounts for 10-15% of all hairs. This phase lasts for about 100 days for hairs on the scalp. During this phase, the hair follicle is completely at rest and the club hair is completely formed. Pulling out a hair in this phase will reveal a solid, hard, dry, white material at the root. About 25-100 telogen hairs shed normally each day.

Anagen: Anagen is the active phase of the hair. The cells in the root of the hair are dividing rapidly, and new hair is formed. Lasting from 2-6 years, scalp hair in this stage grows about 1 cm per month (less than half an inch). Some people have difficulty growing their hair beyond a certain length because they have a short active phase of growth. On the other hand, people with very long hair have a long active phase of growth.