The telogen phase is the resting stage of the hair growth cycle, during which a hair follicle stops producing new hair and holds a fully formed, non-growing strand in place. On a healthy scalp, about 9 to 15 percent of hairs are in the telogen phase at any given time, and this resting period typically lasts two to four months before the follicle reactivates and begins growing a new hair.
How the Hair Cycle Works
Every hair follicle on your body cycles independently through three main phases. The anagen phase is the active growth period, lasting roughly four years for scalp hair. During anagen, cells in the follicle divide rapidly and push the hair shaft upward. Next comes catagen, a short transition lasting a few weeks, during which the follicle shrinks to about five-sixths of its normal diameter as the lower portion breaks down. Then the follicle enters telogen, where it sits quietly for two to four months before the cycle restarts.
Because each follicle operates on its own timeline, you don’t lose all your hair at once. At any moment, the vast majority of your scalp hair (around 85 percent) is actively growing while a small fraction rests in telogen. Body hair follows a different balance: 40 to 50 percent of trunk hair can be in the telogen phase simultaneously, which is why body hair stays much shorter than scalp hair.
What a Telogen Hair Looks Like
During telogen, the base of the hair shaft hardens into a small, rounded bulb shape. This is why telogen hairs are called “club hairs.” The shaft is fully keratinized, meaning its protein structure is complete and no further growth will occur. If you pull out a telogen hair or find one that has shed naturally, you can spot the club shape at the root end: a smooth, pale, bulbous tip with no pigment or fleshy tissue attached.
Under a microscope, dermatologists can distinguish between early and late telogen hairs. Early telogen roots still have traces of the outer sheath surrounding a well-defined club. Full telogen hairs have lost those remnants but retain a clean, rounded tip. Hairs that are actively being released show a more ragged, scalloped edge at the base, signaling they’ve moved into the final shedding stage.
Telogen vs. Exogen: Resting and Shedding Are Different
A common misconception is that telogen is when your hair falls out. It’s actually not. The telogen phase is purely a resting period where the old hair sits anchored in the follicle while the follicle itself is dormant. The actual release of the hair shaft happens during a distinct phase called exogen.
During exogen, the attachments holding the club hair in place gradually dissolve, and the strand loosens until it falls out or is displaced by brushing or washing. Meanwhile, underneath, a new anagen hair has already started growing. This new hair physically pushes the old club hair upward and out of the follicle. So the shedding you notice in the shower is the tail end of a process that started months earlier when those hairs first entered telogen.
What Pushes Too Many Hairs Into Telogen
Losing 50 to 100 hairs a day is normal. But when a large percentage of follicles get pushed into telogen simultaneously, the shedding that follows two to three months later can be alarming. This condition is called telogen effluvium, and it’s diagnosed when more than 25 percent of follicles are found in the telogen phase (normal is around 9 to 15 percent).
The triggers are almost always some form of significant physical or emotional stress that disrupts the normal hair cycle. Common causes include:
- Postpartum hormone shifts: During pregnancy, high estrogen levels keep more hairs in the growth phase longer than usual. After delivery, estrogen drops sharply, and those extra hairs enter telogen all at once, leading to noticeable shedding around three months postpartum.
- High fever or severe illness: Infections, major surgeries, and significant blood loss can trigger a wave of follicles to shift into rest.
- Crash dieting or malnutrition: Sudden caloric restriction signals the body to conserve resources, and hair growth is one of the first things deprioritized.
- Severe emotional stress: Prolonged psychological distress raises cortisol, which directly affects how hair follicles cycle.
In telogen effluvium, the hair loss is diffuse rather than patchy, and it rarely exceeds 50 percent of total scalp hair. A simple pull test can help identify it: if more than 10 percent of gently tugged hairs come out easily from various areas of the scalp, excessive shedding is likely occurring. The reassuring part is that telogen effluvium is almost always temporary. Once the triggering stress resolves, follicles re-enter anagen and hair density gradually returns over six to twelve months.
Hormones That Influence the Telogen Phase
Several hormones play direct roles in how long the telogen phase lasts and how many follicles enter it. Estrogen is one of the most powerful: it can essentially pause the hair cycle clock in telogen, keeping follicles dormant for longer. This is why hormonal shifts around menopause or after stopping birth control can change shedding patterns noticeably.
Thyroid hormones regulate how frequently follicles cycle through anagen. An underactive thyroid slows the rate at which follicles re-enter the growth phase, which means more hairs stay in telogen longer and overall hair density drops. Cortisol, the body’s primary stress hormone, also affects follicle cycling, which explains the direct link between chronic stress and hair thinning.
Seasonal Patterns in Telogen Shedding
If you feel like you lose more hair at the end of summer, you’re not imagining it. Studies tracking hair shedding across European populations consistently find that the highest proportion of telogen hairs occurs in late summer, with shedding peaking in late summer and early fall. A smaller, less dramatic peak appears in spring.
The lowest telogen rates occur in late winter. The likely explanation is tied to daylight: as days lengthen in summer, more follicles shift into the telogen resting phase, and those hairs are released a few months later as fall begins. From an evolutionary perspective, this may have kept a thicker layer of resting hair on the scalp during the sunniest months, offering some protection from UV exposure before the strands were eventually shed. This seasonal variation is subtle enough that most people don’t notice it, but it can amplify concerns for anyone already experiencing stress-related thinning during the same window.