The three stage cycle of hair growth

PHASE 1 – Anagen or ‘Growing’ phase

  • hair shaft diameter increases
  • hair reaches maximum length
  • lasts around 33 months

PHASE 2 – Catagen or ‘Transitional’ phase

  • hair begins to stop growing
  • lasts around 2-3 weeks

PHASE 3 – Telogen or ‘Resting’ phase

  • hair stops growing completely
  • hair shedding begins
  • lasts around 5-6 weeks

The ‘Growth’ phase

PHASE 1 – the Anagen or growing phase

The Anagen phase is the growing phase, or the 'on' phase. It typically lasts for an average of approximately 1,000 days (33 months) in the human scalp.

During the Anagen phase a new hair begins when a group of cells at the base of the hair – the dermal papilla – multiply rapidly.

The hair shaft grows in diameter and the hair reaches maximum length. As new cells form, older cells move upwards and form the hair shaft. Keratin and other proteins form the hair itself.

The ‘Transitional’ phase

PHASE 2 – the Catagen or transitional or regressive phase

Eventually, the cells at the base of the hair stop multiplying. As a result, the hair stops growing before the resting phase begins.

This Catagen phase lasts about 2 to 3 weeks.

The ‘Resting’ phase

PHASE 3 – the Telogen or resting phase

The Telogen is the final resting stage, or 'off' phase which lasts for about five or six weeks in a healthy follicle.

Towards the end of the Telogen phase the hair follicle re-enters the growth phase.

A new hair in the Anagen phase develops and forces the old Telogen hair out.

Every day about 100 old hairs are shed before new hairs replace them.

At any one time around 90% of most people's hair follicles are in the Anagen, or growing, phase and approximately 10% are in the Telogen, or resting, phase.