The growth cycle of human hair Human hair growth can be divided into three phases: the anagen (growth) phase, the catagen (transition) phase, and the telogen (resting) phase. In the anagen phase the papilla induces basal cells to begin development of a new hair. The new hair, growing both upward and downward, moves alongside the old hair and eventually pushes it out of the hair follicle. Hair growth stops in the catagen phase. Basal cells and the follicle migrate upward in the telogen phase. (more) Why Does Head Hair Grow Indefinitely but Not Body Hair? Written by Kara Rogers Kara Rogers is the senior editor of biomedical sciences at Encyclopædia Britannica, where she oversees a range of content from medicine and genetics to microorganisms. She joined Britannica in 2006 and... Kara Rogers Fact-checked by Britannica Editors Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree.... Britannica Editors Last updated Apr. 6, 2026 •History The key difference between the growth of head hair and body hair lies in the duration of the active growth phase: Scalp hair follicles remain in active growth for several years, whereas follicles in other body regions enter the transition and resting phases much sooner. Hair growth occurs in a repeating cycle consisting of three phases: anagen (active growth), catagen (a brief transitional phase), and telogen (resting and shedding). In scalp hair follicles, the anagen...

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