Telogen Effluvium

What is telogen effluvium?

Telogen effluvium (TE) is a temporary disruption of the hair growth cycle in which an unusually high number of follicles simultaneously shift from the growth phase into the resting phase (telogen). The result is diffuse shedding across the scalp, typically appearing two to three months after an identifiable triggering event. ^[1]

Unlike androgenetic alopecia, telogen effluvium does not damage the hair follicle itself. It is a cycle disruption, not a structural one. In most cases the condition resolves on its own once the underlying trigger is addressed.

The condition was first formally described by dermatologist Albert Kligman in 1961. ^[1] This page focuses on telogen effluvium as a condition. For the specific question of stress, timing, and chronic stress biology, read our guide on stress and hair loss.

Symptoms

The defining feature of telogen effluvium is diffuse shedding. Hair loss is spread across the entire scalp rather than concentrated at the hairline or crown. Most people notice it on their pillow, in the shower drain, or on their brush.

Under normal conditions, the average person sheds between 50 and 100 hairs per day. In telogen effluvium, that number can rise sharply. In severe cases, up to 70 percent of growing hairs may enter the resting phase simultaneously, producing a daily shed count well above 300 hairs. ^[1]

Because the shedding is diffuse and the follicles remain intact, regrowth occurs naturally once the trigger is resolved. The hair does not fall out in patches and the scalp typically shows no visible inflammation or scarring.

Causes

Telogen effluvium is triggered by events that represent a significant physiological or metabolic stress to the body. In clinical practice, the most useful first step is to look for concrete triggers rather than assuming the cause is everyday stress.

The most well-documented triggers include illness, surgery, nutritional deficiency, thyroid dysfunction, psychological stress, childbirth, and medication changes.

Physical illness and surgery

High fever, serious infection, major surgery, or significant blood loss can all precipitate a shedding episode. The more severe the physiological event, the more follicles are affected.

Nutritional deficiency

Low ferritin, the body's iron store, is one of the most commonly missed causes of diffuse hair shedding. Inadequate protein intake and severe caloric restriction, such as crash dieting or extended periods of poor nutrition, are also reliable triggers. ^[1]

Thyroid dysfunction

Both an underactive and an overactive thyroid can disrupt the hair cycle and produce diffuse shedding that resembles telogen effluvium. Thyroid function is often worth checking when the cause is not immediately clear. ^[1]

Psychological stress

Prolonged, high-intensity emotional stress can trigger shedding, though it generally needs to be more severe and sustained than everyday work pressure or mild anxiety. When stress affects sleep, eating, weight, or recovery from illness, it becomes more relevant clinically.

Childbirth and medication changes

Postpartum telogen effluvium is one of the most recognised forms and often the first time many women encounter the condition. Certain medications can also trigger a shedding episode as a side effect. If shedding began shortly after starting or stopping a medication, this is worth discussing with a physician.

Acute versus chronic telogen effluvium

Telogen effluvium presents in two distinct forms, and the distinction has practical implications.

Acute telogen effluvium resolves within six months of the triggering event ending. This is by far the more common form. Once the trigger is removed, the hair cycle normalises and regrowth follows.

Chronic telogen effluvium is defined as shedding that persists beyond six months. This form almost always indicates that a contributing factor is still active, whether an unresolved nutritional deficiency, an untreated thyroid condition, or ongoing significant stress. Identifying and addressing the underlying cause is the central step in treatment. ^[1]

Diagnosis

Telogen effluvium is typically diagnosed through a combination of clinical assessment and medical history.

A physician will ask about the timing and pattern of shedding, recent life events, dietary changes, illnesses, surgeries, and medications. The two to three month gap between trigger and shedding onset is an important diagnostic clue, and patients are often surprised when a physician asks about events that occurred well before the shedding started.

A pull test can help assess the degree of active shedding. In a gentle pull of 20 to 60 hairs, more than 10 percent releasing easily suggests elevated active shedding. Dermoscopy, also called trichoscopy, allows closer examination of the follicles.

Blood work is often useful and should at minimum cover ferritin, thyroid-stimulating hormone (TSH), and a basic blood count. These tests can identify deficiencies or conditions that, if left unaddressed, would prevent recovery. ^[1]

Differentiating telogen effluvium from androgenetic alopecia is important, particularly in men who carry a genetic predisposition to pattern hair loss. A bout of telogen effluvium can occasionally unmask androgenetic alopecia that was already developing beneath the surface. Once the diffuse shedding resolves, a pattern of thinning may remain. A physician assessment is the most reliable way to distinguish the two. For a broader overview of possible causes, read hair loss causes.

Treatment

The most effective intervention in telogen effluvium is identifying and resolving the underlying trigger. Treatment is therefore guided by the cause: nutrition, thyroid health, recovery from illness, medication review, or another medical factor. In many cases, addressing the cause is the only treatment needed.

If low ferritin, poor protein intake, or another deficiency is identified, correcting it through diet or supplementation under medical guidance is the primary step. Recovery of hair density typically follows, though it takes time.

If thyroid dysfunction or another medical condition is driving the shedding, treatment of that condition is the priority.

Minoxidil can support and accelerate regrowth during recovery, though it does not address the underlying cause. Whether it is appropriate depends on the clinical picture and should be assessed by a physician. Finasteride is not a treatment for telogen effluvium. It is relevant only if androgenetic alopecia is confirmed or suspected alongside the TE diagnosis.

What to expect during recovery

Shedding typically peaks two to four months after the triggering event, then gradually slows as the cycle normalises. Most people notice a significant reduction in shedding within three to six months of the trigger resolving.

Full density recovery takes longer. New hairs grow back shorter and finer at first, and it can take 12 to 18 months from the point the trigger is resolved for hair to return to its previous thickness. Progress often feels slow because the early regrowth is not yet visible at full length.

If shedding persists beyond six months without improvement, or if blood work reveals an ongoing deficiency, the underlying cause is likely still active and further evaluation is warranted. ^[1]

Prevention

Telogen effluvium cannot always be prevented, since many triggers are not predictable or controllable. What can help is recognising the condition early and identifying the cause promptly, which shortens the time to recovery.

Maintaining adequate iron and protein intake, addressing thyroid health, and managing chronic stress where possible reduce the risk of prolonged episodes. If you notice diffuse shedding following a significant event, illness, or period of poor nutrition, early blood work can clarify whether a correctable deficiency is involved.

If you are unsure whether what you are experiencing is telogen effluvium or a different form of hair loss, a physician assessment is the clearest next step. Blood work and a proper hair evaluation can often answer the question in a single consultation.