What Is The Telogen Phase Of Hair Growth?

Every hair on your head is somewhere in a life cycle right now — growing, transitioning, or resting before it falls out. The telogen phase is that resting stage. It is the final phase of the hair growth cycle, a period of roughly two to three months when a hair strand stops growing, stays anchored in the follicle, and eventually sheds to make room for a new hair.

Telogen is normal. Everyone has hairs in this phase at all times. In fact, at any given moment, somewhere between 10 and 15 percent of the hairs on a healthy scalp are in telogen. The phase only becomes a concern when too many hairs enter it at once — a condition called telogen effluvium — which produces noticeable shedding weeks or months later.

What Is The Telogen Phase Of Hair Growth?

The telogen phase is the resting period of the hair follicle cycle. During this stage, the hair shaft is fully formed but no longer growing. It sits in the follicle, held in place by a small, club-shaped root, until the next growth cycle pushes it out.

The hair growth cycle has four phases. Three are well established in the medical literature:

• Anagen — the active growth phase, lasting two to seven years on the scalp
• Catagen — a short transition phase of about two to three weeks, when growth stops and the follicle begins to shrink
• Telogen — the resting phase, lasting roughly two to three months
• Exogen — the shedding phase, when the resting hair is released

Some sources fold exogen into telogen. The distinction matters because shedding is not a single moment. Hairs in telogen are not all released at once. They shed gradually, which is why a healthy scalp loses about 50 to 100 hairs a day without any visible thinning.

Hair length is determined by how long it stays in anagen, not telogen. The telogen phase runs on a fairly fixed clock regardless of how long the hair grew. This is why people with very long hair do not have longer resting periods — they have longer growth periods.

What Happens To A Hair During The Telogen Phase?

During telogen, the follicle is essentially dormant. The lower portion of the follicle — the part that was actively building the hair shaft — has shrunk and pulled away from the blood supply that fed it.

The hair itself is fully keratinized at this point. It is a complete, dead structure made of protein. No further growth or change happens to it while it rests. The dermal papilla, the small cluster of cells at the base of the follicle, is quiet. It is not signaling new growth yet.

What the follicle is doing during this time is preparing for its next cycle. Stem cells in a region called the bulge, near the upper part of the follicle, are being readied to regenerate the lower follicle and start a new anagen phase. When that new hair begins to form, it pushes the old resting hair up and out. That is the shedding you see.

This is a useful point to understand: the hair that falls out during telogen shedding is not being “lost” in a damaging sense. It is completing a normal cycle. A new hair is typically already forming in the same follicle beneath it.

What Causes Too Many Hairs To Enter Telogen At Once?

Telogen effluvium happens when a stressor pushes an abnormal number of follicles out of the growth phase and into the resting phase at the same time. Because telogen lasts about two to three months, the shedding usually appears two to three months after the trigger. This delay is one of the most misunderstood parts of the condition.

Common triggers include:

• Major physical stress such as surgery, serious illness, or trauma
• Significant weight loss or severe calorie restriction
• Childbirth — a well-documented trigger, since many follicles shift into telogen after delivery
• High fever or severe infection
• Some medications, including certain antidepressants, blood pressure drugs, and hormonal treatments
• Thyroid disorders and other endocrine conditions
• Iron deficiency, particularly when ferritin levels are low
• Emotional stress, though the evidence here is less consistent than for physical triggers

Not every trigger affects every person the same way. Two people can experience the same illness and only one develops noticeable shedding. The reasons for this variation are not fully understood.

An important distinction: telogen effluvium is different from androgenetic alopecia, the inherited pattern hair loss that affects men and women differently. Telogen effluvium is typically diffuse — spread across the whole scalp — while pattern hair loss follows a predictable shape. The two can also occur together, which complicates diagnosis.

How Long Does Telogen Effluvium Last?

For most people, telogen effluvium resolves on its own. Once the trigger is removed, hairs gradually return to the growth phase, and shedding slows over a period of months.

The timeline varies. Many cases improve within six to twelve months. Some last longer, especially when the trigger cannot be fully identified or corrected. Chronic telogen effluvium, defined as shedding lasting more than six months, is recognized in dermatology and tends to affect women more often than men.

It is worth being honest about what the evidence does not show. There is no single treatment proven to speed recovery from telogen effluvium in all cases. When a specific cause is found — low iron, thyroid dysfunction, a medication — correcting it often helps. When no cause is identified, management focuses on reassurance and monitoring, since most cases do improve. Some clinicians recommend nutritional support or topical treatments, but these are not uniformly supported by strong trial evidence, and results vary.

This is a condition where the delay between trigger and shedding confuses many people. Someone who recovers from a severe illness in January may not notice hair loss until March or April. By then, they often assume something new is wrong. Usually, nothing new is wrong. The earlier event is the cause.

How Is Telogen Effluvium Diagnosed?

Diagnosis is usually clinical — based on history and examination — rather than on a single test. A doctor will typically ask about recent illness, surgery, weight changes, medications, and life stress in the months before shedding started.

A simple test called the hair pull test can help. A clinician grasps a small bundle of hair and applies gentle traction. If several hairs come out easily, it suggests active shedding. The test is quick and does not require special equipment, though its results depend on technique and where on the scalp it is performed.

Blood tests are commonly ordered to look for underlying causes. These often include:

• Complete blood count and ferritin (iron stores)
• Thyroid stimulating hormone
• Basic metabolic panel
• Vitamin D and sometimes vitamin B12

These tests are used to rule out conditions that can mimic or contribute to telogen shedding. They are not specific to telogen effluvium itself. A normal result does not rule the condition out, and an abnormal result does not automatically confirm it.

In some cases, a scalp biopsy may be considered, particularly when the diagnosis is unclear or when pattern hair loss is suspected alongside telogen shedding. Biopsy is not routine and is reserved for situations where the clinical picture is ambiguous.

Telogen vs. Other Hair Growth Phases

Understanding how telogen compares to the other phases helps clarify why it matters. The table below summarizes the main differences.

The proportions matter too. On a healthy scalp, the large majority of hairs are in anagen at any given time. Roughly 10 to 15 percent are in telogen. In telogen effluvium, that proportion rises, which is why shedding increases.

One clarification worth making: the phases are not synchronized across the scalp. Each follicle cycles independently. This is why you do not shed all your hair at once, and why hair loss from telogen effluvium is usually gradual rather than sudden.

When Should You See A Doctor About Hair Shedding?

Shedding is worth a medical evaluation when it is heavy, persistent, or accompanied by other symptoms. A doctor can help distinguish telogen effluvium from other causes of hair loss, some of which need different treatment.

Signs that warrant a check include:

• Shedding that continues for more than six months
• Visible thinning or bald patches
• Shedding along with fatigue, weight change, or other systemic symptoms
• Shedding that starts after a new medication
• Scalp pain, itching, or scaling

It is also reasonable to seek evaluation simply because the shedding is distressing. Hair loss affects quality of life, and that is a legitimate reason to ask for help. A clinician can explain what is likely happening and whether any testing is needed.

What you should not expect is a guaranteed quick fix. Telogen effluvium often resolves with time, and the most useful steps are usually identifying and addressing any underlying trigger. Patience is genuinely part of the process, even though that is frustrating to hear.