Hair cycle
The repeating growth, transition and rest phases every hair follicle moves through, and why the cycle explains normal shedding and delayed hair fall.
Supriya Bhandary
Founder, Soumm · 4 September 2026 · Updated 14 October 2026
What is the hair cycle?
The hair cycle is the repeating sequence of growth, regression and rest that every hair follicle moves through. Follicles cycle independently of one another, which is why hair is shed a little at a time rather than all at once. (Paus & Cotsarelis, 1999)
The phases
Anagen (growth): the active phase, lasting roughly two to seven years on the scalp. Around 85 to 90 percent of scalp hairs are in anagen at any time, and its length largely sets how long your hair can grow.
Catagen (transition): a short phase of about two to three weeks in which the follicle regresses.
Telogen (rest): lasts around three months. Roughly 10 to 15 percent of scalp hairs are resting at any time.
Exogen (release): the old hair is shed, often as a new anagen hair begins to grow beneath it.
Why it matters
Because a hair rests for months before it falls, shedding often reflects events from two to three months earlier. This is the pattern behind telogen effluvium. Losing around 50 to 100 hairs a day is a normal part of the cycle. (American Academy of Dermatology)
Practical note
Sudden, heavy or patchy shedding, or shedding that continues beyond about six months, deserves a dermatologist's assessment.
See also: Anagen Phase, Shedding, Telogen Effluvium.
Sources
American Academy of Dermatology. Do you have hair loss or hair shedding?
Paus R, Cotsarelis G. The biology of hair follicles. N Engl J Med. 1999;341(7):491–7.
Questions
On the scalp, the growth phase (anagen) typically lasts about two to seven years, which is why some people can grow much longer hair than others.
A shock can push many follicles into the resting phase at once. Those hairs are shed around two to three months later, when the resting phase ends.
Yes. Shedding around 50 to 100 hairs a day is typical as hairs complete their cycle and are replaced.