Catagen Phase

The Catagen Phase is the short transitional stage of the hair growth cycle that occurs between the active growth phase (anagen) and the resting phase (telogen). During this phase, which typically lasts about two to three weeks, the lower portion of the hair follicle undergoes involution: the follicle shrinks, the hair shaft detaches from its blood supply, and growth ceases as the follicle prepares to enter the resting phase.

Only a small proportion of hairs are in catagen at any one time because it is brief, but correct timing of this stage is important for healthy hair renewal; disturbances in the sequence or timing of anagen, catagen, and telogen can contribute to increased shedding or thinning. Recognizing how the Catagen Phase fits into the overall hair cycle can help explain patterns of temporary hair loss and guide when to seek evaluation or management for hair concerns.