First published: December 2025 · Last updated: September 2026
The hair growth cycle consists of anagen, catagen, and telogen phases that regulate how hair grows, rests, and sheds. Understanding this cycle explains normal shedding, delayed regrowth after hair transplant surgery, and why visible results develop gradually over time.
Key Facts
Three phasesAnagen, catagen, telogen
AnagenActive growth lasting years on the scalp
CatagenBrief regression between growth and rest
TelogenRest, then release of the hair
Resting at any timeRoughly 10-15% of hairs
After surgeryGrafts enter rest, so the hair sheds first
Every follicle runs its own clock. Hairs do not cycle together, which is why humans shed continuously instead of moulting. At any moment a scalp holds hairs in three different states, and roughly 10 to 15 per cent of them are resting rather than growing (Hoover, Alhajj & Flores, Physiology, Hair, StatPearls).
The ring is divided by how many scalp hairs occupy each phase at any moment, not by how long each phase lasts.
Phase
What happens
What it determines
Anagen
Active growth, lasting years on the scalp
Maximum length the hair can reach
Catagen
Brief transition; the follicle regresses
End of that growth run
Telogen
Rest, then the hair is released
Normal daily shedding
Anagen length is the reason hair on different parts of the body stops at different lengths. Scalp anagen runs for years; on the body it is far shorter, so those hairs reach a few centimetres and let go. The follicle is not weaker — its growth run is simply shorter, and that limit travels with it if it is moved.
Surgery pushes grafts into the cycle deliberately. The trauma of being moved sends a transplanted follicle into rest, so the visible hair is shed within the first weeks. That shedding is the cycle working, not a failure. New growth appears when the follicle re-enters anagen, which is why nothing about a result can be judged in the first months.
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