Cortisol
A hormone released under stress; implicated in changes to the hair growth cycle.
Soumm
4 September 2026
Definition
A glucocorticoid hormone central to the body’s stress response, with wide effects on metabolism, immune function and tissue repair.
Sustained elevation is associated with earlier entry of follicles into their resting phase.
What is uncertain
The threshold at which everyday stress becomes significant for hair is not well defined, and individual variation is large.
See also: Stress, Telogen Effluvium.
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