The catagen phase is a brief transitional stage in the hair growth cycle when a hair follicle stops producing new hair and begins to shrink. It lasts about two weeks and serves as the bridge between active growth (anagen) and the resting period (telogen) that eventually leads to shedding. At any given time, only a small fraction of the hairs on your head are in this phase, which is why you don’t notice it happening.
Where Catagen Fits in the Hair Cycle
Every hair on your body cycles through three main phases. The first, anagen, is the active growth stage. On your scalp, anagen lasts anywhere from two to seven years, which is why head hair can grow so long. Once a follicle’s growth period ends, it enters catagen for roughly two weeks. After that comes telogen, a resting phase lasting several months, at the end of which the hair sheds and a new anagen phase begins.
These phases aren’t synchronized across your scalp. Each follicle runs on its own clock. The vast majority of your hair, roughly 85 to 90 percent, is in the anagen phase at any moment. Only about 1 to 3 percent is in catagen. This staggered timing is why you shed some hairs daily without ever developing bald patches from the process alone.
What Happens Inside the Follicle
During anagen, a cluster of rapidly dividing cells at the base of the follicle (the matrix) pushes new hair upward. The follicle sits deep in the skin, anchored around a small ball of supportive tissue called the dermal papilla, which feeds it growth signals and nutrients through a blood supply. Catagen dismantles this arrangement in an organized way.
The process starts when signaling switches within the matrix and surrounding tissue trigger those rapidly dividing cells to undergo coordinated, programmed cell death. This is the body’s controlled demolition: the lower portion of the follicle collapses and shrinks. The follicle physically detaches from the dermal papilla, cutting the hair off from its blood supply and the signals that were driving growth. Hair growth slows dramatically and then stops.
As the lower follicle retracts upward, the inner root sheath, a protective sleeve that surrounds the growing hair shaft, begins to break down. The outer root sheath thins. The follicle that was once long and deeply rooted becomes shorter and structurally incomplete. By the end of catagen, the follicle may be a fraction of its anagen length.
How Club Hair Forms
One of the most important outcomes of catagen is the creation of what’s called a “club hair.” As the hair separates from the base of the follicle and loses its blood supply, the root end hardens into a small, rounded bulb. This club-shaped tip is what you sometimes see on a hair that falls out naturally, a tiny white dot at the end.
The club hair stays loosely anchored in the shrunken follicle even though it’s no longer growing. It can remain in place for the entire telogen resting period, which lasts around two to four months on the scalp. Eventually, a new anagen phase begins beneath it, and the emerging hair pushes the old club hair out. This is the shedding you notice in your brush or shower drain.
What Triggers the Transition
The shift from active growth into catagen isn’t random. It’s driven by molecular signals produced within the follicle itself. When certain growth-promoting signals decrease and regression-promoting signals increase, the matrix cells receive the cue to stop dividing and begin their programmed shutdown. The precise timing varies by follicle and is influenced by genetics, hormones, and overall health.
This is why conditions that affect hormone levels, nutritional status, or inflammatory signaling can disrupt the hair cycle. If too many follicles are pushed into catagen (and then telogen) at once, the result is noticeable thinning or shedding. Stress-related hair loss, for instance, works partly through this mechanism: a wave of follicles exits anagen prematurely, and the increased shedding shows up a few months later when those hairs reach the end of telogen.
Catagen vs. Telogen
People sometimes confuse these two phases because neither involves active hair growth, but they’re structurally distinct. A catagen follicle is in the process of shrinking. Its inner root sheath may still be partially present, and the follicle bulb is collapsing. The tissue is actively remodeling.
A telogen follicle, by contrast, has finished that remodeling. The structure is loose and minimal. The inner root sheath is gone entirely, and the hair shaft sits in its socket with very little anchoring it. Some telogen hairs have already fallen out, leaving empty cavities where the shaft used to be. Think of catagen as active demolition and telogen as the quiet period before rebuilding starts.
Why Catagen Matters for Hair Health
Because catagen is so short and involves such a small percentage of your hair at any time, it’s easy to overlook. But it plays a critical role in follicle renewal. The controlled cell death that occurs during catagen clears out the old growth machinery, and the dermal papilla, though detached, is preserved. It stays near the base of the shrunken follicle, ready to reconnect and restart growth when the next anagen phase begins.
Without a properly functioning catagen phase, follicles can’t reset. Research into hair loss increasingly focuses on what goes wrong at these transitions, whether follicles fail to re-enter anagen after telogen, or whether premature catagen entry shortens the growth window and produces thinner, shorter hairs over time. Pattern hair loss, for example, involves a progressive shortening of the anagen phase, meaning follicles spend less time growing and cycle through catagen and telogen more frequently, eventually producing hairs too fine and short to be visible.