Telogen Effluvium

What is telogen effluvium?

In telogen effluvium (TE), an unusually high number of follicles shift from the growth phase into the resting phase (telogen) at the same time. The hairs do not fall out straight away but at the end of this resting phase, which explains the delay after the trigger. ^[1][2] Telogen effluvium is regarded as one of the most frequent causes of diffuse hair loss. Its exact frequency is unknown, partly because many mild cases are never seen by a doctor. ^[1][7]

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 term goes back to dermatologist Albert Kligman, who described the condition in 1961. ^[3] 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.

Key facts and figures

The figures below come from the reviews and specialist sources listed at the end of this page. They describe typical courses and do not predict the result for any one person.

• Losing 50 to 100 hairs a day is normal. ^[5]
• Around 85% of scalp hairs are in the growth phase and around 15% in the resting phase. Under heavy physical stress, up to about 70% of growing hairs can shift into the resting phase. ^{[1] [6]}
• Increased shedding typically starts two to three months after the trigger, and usually two to four months after childbirth. ^{[1] [2] [3]}
• Shedding lasting less than six months is called acute telogen effluvium, longer than six months chronic telogen effluvium. ^{[2] [3]}
• According to a review, acute telogen effluvium resolves in around 95% of cases. ^[2]
• Regaining previous fullness typically takes six to nine months, and full density sometimes up to a year. ^{[1] [5]}

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.

Normally only a small share of scalp hairs is in the resting phase, the values are listed above under «Key facts and figures». Under sustained significant stress on the body, far more follicles shift there at the same time. ^[1][6] In telogen effluvium, daily loss can therefore rise sharply, because follicles leave the growth phase prematurely and the hairs are then shed in larger numbers. ^[2][3]

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 triggers described include illness, surgery, nutritional deficiency, thyroid dysfunction, psychological stress, childbirth, and medication changes.

Physical illness and surgery

Acute febrile illness, severe infection, major surgery or severe trauma can all precipitate a shedding episode. ^[1]

Nutritional deficiency

Low ferritin, the body's iron store, is often named as a possible factor in diffuse hair shedding, although the evidence is mixed. ^[3] Inadequate protein intake and severe caloric restriction, such as crash dieting or extended periods of poor nutrition, are also common triggers. ^[1]

Thyroid dysfunction

Both an underactive and an overactive thyroid can lead to telogen effluvium. ^[2] If symptoms point to hypothyroidism, a thyroid test is warranted. ^[1]

Psychological stress

Emotional strain is described as a possible trigger. ^[3] How severe or prolonged it has to be is not clearly established.

Childbirth and medication changes

Postpartum telogen effluvium is one of the most recognised forms. It typically begins two to four months after delivery. ^[3] Certain medications, such as beta-blockers, retinoids or anticoagulants, have also been linked to telogen effluvium. ^[1] 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 is defined as shedding that lasts less than six months. ^[2][3] Once the trigger is removed, the hair cycle normalises and regrowth follows.

Chronic telogen effluvium is defined as shedding that persists beyond six months. ^[2][3] This form can indicate 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]

How it differs from androgenetic alopecia

The most important distinction is androgenetic alopecia, hereditary hair loss. The two forms differ in onset, pattern and course. Telogen effluvium usually starts suddenly, around two to three months after a trigger, and spreads evenly across the whole scalp. ^{[1] [2]} Androgenetic alopecia starts gradually and follows a pattern, in men with a receding hairline and thinning at the crown, in women with a widening central parting. In telogen effluvium, more whole hairs fall out, while in androgenetic alopecia the hairs mainly become thinner and finer.

Both can occur together, especially in men with a genetic predisposition. Telogen effluvium can unmask androgenetic alopecia that was already developing underneath. Once the diffuse shedding settles, a thinning pattern then remains. Round, patchy bald spots fit neither form and point more towards alopecia areata. ^[6] A medical assessment is the most reliable way to tell these forms apart. The guide hair loss causes gives a broader overview.

When to see a physician

Mild telogen effluvium with a clear explanation, for example a few weeks after flu with a high fever, often resolves on its own. An assessment still makes sense if you cannot identify a trigger, if the shedding is very heavy or if it lasts longer than six months. ^{[2] [3]}

Certain circumstances are also a reason for a medical assessment. These include fatigue, paleness or sensitivity to cold, which can point to iron deficiency or a thyroid disorder, a diet low in iron or protein, a new or stopped medication, a recent birth, or bald patches, redness, scaling or pain of the scalp. ^[1] Do not stop a new medication on your own because of hair loss, discuss it with a physician first. If your hair does not return to its previous density after recovery, androgenetic alopecia may be behind it and needs its own assessment.

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 gap of two to three months between trigger and shedding onset is an important diagnostic clue ^[2], 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 study of 181 participants, 97.2 percent released two hairs or fewer in a pull test at the vertex; more released hairs can point to elevated active shedding. ^[4] Dermoscopy, also called trichoscopy, allows closer examination of the follicles.

Blood tests are recommended when there are concerns about hypothyroidism, a chronic metabolic illness or iron deficiency. To assess iron status, StatPearls names a complete blood count, serum iron, iron saturation and ferritin, and notes that a normal ferritin level does not rule out iron deficiency. ^[1]

Treatment

The most effective intervention in telogen effluvium is identifying and resolving the underlying trigger. Treatment is therefore guided by the cause, for example nutrition, thyroid health, recovery from illness, medication review, or another medical factor. In many cases, addressing the cause is the only treatment needed. ^[1]

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. ^[1]

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

Minoxidil is used in telogen effluvium in some cases, but the evidence is limited and assessed differently in the literature. ^[2][3] 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

In acute telogen effluvium, shedding usually eases gradually as the cycle normalises. According to DermNet, shedding tapers back to normal over six to nine months in most people ^[6], and acute telogen effluvium resolves in the large majority of cases. ^[2] The course varies from person to person. ^[3]

Full density recovery takes longer. According to StatPearls, regrowth can take up to six months to restart and several months to a year to fully restore density. ^[1] The American Academy of Dermatology gives six to nine months as the typical time to regain the previous fullness. ^[5] In some cases recovery remains incomplete. ^[6] New hairs are still short at first, and 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, further medical evaluation is warranted. Shedding that lasts longer than six months is classified as chronic telogen effluvium. ^[2][3]

The care pathway in Switzerland

In Switzerland, the family doctor is the first point of contact for most people with diffuse shedding. Many insured people have chosen a family doctor, HMO or Telmed model, where the first point of contact is set and a referral is usually needed to see a dermatologist. ^[8] This route works well for telogen effluvium, because the search for the trigger often relies on history and blood tests such as a blood count, ferritin or thyroid values. ^[1]

A referral to dermatology makes sense if the picture remains unclear, the shedding becomes chronic or there are signs of another hair or scalp condition. Assessing a possible illness is billed to basic insurance, subject to the deductible and co-payment. ^[8] Telemedicine services specialising in hair loss can help clarify whether telogen effluvium or hereditary hair loss is more likely. Blood tests and warning signs, however, need a physician in person. The guide online doctor for hair loss describes how an online medical assessment works and where its limits are.

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 allows earlier assessment.

Maintaining adequate iron and protein intake, addressing thyroid health, and managing chronic stress where possible can be sensible, although a preventive effect has not been shown for these measures. 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.