Every hair follows its own independent cyclical lifespan, which is why at any given moment only a portion of scalp hair sits in the same phase.
85-90%In anagen (growth) phase
1-2%In catagen (regression) phase
9-10%In telogen (resting) phase
Anagen — The Growth Phase
A period of intense cell division that produces the hair shaft, lasting 3 to 10 years on the scalp. The length of this phase determines the maximum length a hair can reach.
Catagen — The Regression Phase
A roughly two-week transitional phase in which the follicle detaches from the dermal papilla, shrinks, and cell death (apoptosis) begins.
Telogen — The Resting Phase
Lasting 2-3 months, the hair remains loosely anchored in the follicle until a new anagen phase begins and pushes the old strand out — the normal shedding seen in telogen effluvium.
Relevance to transplantation: Transplanted grafts typically enter a temporary telogen phase and shed within 2-4 weeks after surgery — known as "shock loss." This does not mean the follicle has died; the stem cells remain intact beneath the skin, and new growth begins within a few months.