The telogen phase is the resting stage of the hair growth cycle, during which the hair follicle becomes dormant and the hair shaft stops growing. It lasts roughly two to four months on a healthy scalp, and at any given time about 10% to 15% of your scalp hairs are in this phase. Understanding what actually happens during telogen, and what can go wrong, helps explain everything from normal daily shedding to the alarming hair loss that can follow pregnancy or illness.
What Happens Inside the Follicle
During the telogen phase, the hair follicle essentially shuts down. No new cells are produced, the follicle shrinks, and the connection between the hair strand and its blood supply is severed. The result is a “club hair,” a fully formed, fully hardened strand that sits loosely in the follicle with a small, rounded white bulb at its root. If you’ve ever noticed a tiny white dot at the end of a naturally shed hair, that’s the club shape characteristic of a telogen hair.
The follicle isn’t dead during this time. It’s conserving energy and preparing for its next growth cycle. Once the resting period ends, the follicle reactivates, a new hair begins forming at its base, and the old club hair is pushed out. That push is what causes the shedding you see in your brush or shower drain.
How Telogen Fits the Full Hair Cycle
Hair growth moves through three primary stages. The anagen (growth) phase lasts two to seven years and accounts for 85% to 90% of scalp hairs at any moment. The catagen (transition) phase is a brief two-to-three-week window where the follicle begins to shrink. Telogen follows, lasting two to four months before the hair is released and growth restarts.
The body staggers these cycles across roughly 100,000 scalp follicles so that only a small fraction are resting or shedding at once. This staggering is why you lose hair gradually rather than all at once. Normal daily shedding falls between 50 and 150 hairs, nearly all of them telogen club hairs that have reached the end of their resting period.
One detail worth noting: body hair behaves differently. While only about 9% to 15% of scalp follicles sit in telogen at a given time, 40% to 50% of trunk hair follicles are in telogen. That’s why body hair stays short. It spends far less time growing and far more time resting compared to the hair on your head.
Telogen Effluvium: When Too Many Hairs Rest at Once
The most clinically significant thing about the telogen phase is what happens when it’s triggered prematurely in a large number of follicles at the same time. This condition is called telogen effluvium, and it causes diffuse, noticeable hair thinning across the entire scalp.
The mechanism is straightforward. A physiological stressor forces a large wave of actively growing hairs to abruptly shift into the telogen phase. Those hairs then sit dormant for one to six months (three months on average). You won’t notice anything during this resting window because the hairs are still in place. But once those follicles reactivate and new growth begins, the old club hairs are all pushed out around the same time, resulting in dramatic shedding that can exceed 100 hairs per day.
This delay is why telogen effluvium catches people off guard. The shedding typically appears about three months after the triggering event, making it hard to connect cause and effect without thinking back.
Common Triggers
- Postpartum hormone shifts: During the last trimesters of pregnancy, elevated estrogen keeps an unusually high number of follicles in the growth phase. After delivery, estrogen drops sharply, and those follicles enter telogen simultaneously. About 20% of women experience noticeable shedding two to three months postpartum.
- Illness or surgery: High fevers, severe infections, and major surgical procedures are classic triggers.
- Nutritional deficits: Crash dieting, low protein intake, and iron deficiency can all push follicles into early rest.
- Hormonal changes: Hypothyroidism and suddenly stopping estrogen-containing medications (including birth control pills) can trigger a synchronized shedding wave.
- Severe stress or trauma: Both physical trauma and intense psychological stress are recognized triggers.
How Telogen Effluvium Is Identified
A clinician can check for excessive telogen shedding with a simple hair pull test. The test involves grasping a bundle of 50 to 60 hairs close to the scalp and pulling with slow, firm traction. If more than 10% of the hairs in the bundle come out, the result is considered positive for active shedding. The pulled hairs will have the characteristic club shape of telogen hairs rather than the tapered, pigmented roots of hairs still in active growth.
No biopsy or blood work is needed to identify telogen effluvium itself, though blood tests may be useful to uncover an underlying trigger like thyroid dysfunction or iron deficiency.
Recovery Timeline
The reassuring truth about telogen effluvium is that it’s almost always reversible. Once the triggering factor is removed or resolved, the affected follicles cycle back into growth normally. Shedding typically stops within three to six months after the trigger is addressed. New growth becomes visible in a similar timeframe, but cosmetically significant regrowth, enough that your hair looks and feels full again, generally takes 12 to 18 months.
In rare cases, the trigger persists (ongoing nutritional deficiency, unmanaged thyroid disease, chronic stress), and shedding can become chronic. Identifying and correcting the root cause is the most effective path to recovery, since the follicles themselves remain healthy and capable of producing new hair throughout the process.
Key Facts About Telogen at a Glance
- Duration: Two to four months on the scalp.
- Percentage of scalp hair in telogen: Roughly 10% to 15% at any time.
- Hair state: Fully formed club hair, no longer receiving blood supply or growing.
- Normal daily shedding: 50 to 150 telogen hairs.
- Follicle status: Dormant but alive, preparing for the next growth cycle.
- Body hair difference: Up to 50% of trunk hair sits in telogen, compared to roughly 10% to 15% on the scalp.