What is telogen effluvium? Hair loss after stress, illness and childbirth

What is telogen effluvium?

Telogen effluvium happens when more hair follicles than usual enter the resting phase at the same time and, a few months later, these hairs fall out together. Telogen is the name of the hair’s resting phase; effluvium means shedding.

Every follicle (hair root) on the scalp follows a cycle made up of growth, transition and resting phases; we describe this cycle in our article on the hair growth cycle. Normally, about 10–15% of hairs are in the resting phase, and some of them fall out every day. In telogen effluvium, this share rises noticeably; that is why you see more hair than usual on your comb, on your pillow and in the shower.

In telogen effluvium, the follicles are not permanently damaged; a new hair grows from the same follicle to replace the one that fell out. That is why telogen effluvium does not lead to baldness on its own. Even so, the hair can thin noticeably, and this can be a worrying time for many people.

What causes telogen effluvium?

When the body is put under serious strain, some of the follicles in the growth phase end this phase earlier than usual and enter the resting phase. The resting phase lasts about three months; at the end of it, the follicle starts producing a new hair and the old one falls out. That is why the shedding does not start at the same time as the trigger but usually around two to three months later. This delay is also why many people do not connect the shedding with its cause.

Commonly reported triggers include:

• Illnesses with a fever: infections that cause a high fever or are severe, such as the flu or COVID-19.
• Giving birth: During pregnancy, hormones keep hairs in the growth phase longer than usual; after the birth, these hairs enter the resting phase all at once. The shedding often becomes noticeable a few months after giving birth; in many women, the hair returns to its former fullness by the time the baby is one year old.
• Major physical strain: surgery, an accident or a serious illness.
• Rapid weight loss and strict diets: especially diets that are very low in calories or do not provide enough protein.
• Severe emotional stress: grief, a separation or long periods of heavy pressure. It is difficult, however, to tell how much of an effect stress alone has.
• Certain medications: some medications that have just been started or changed (for example, some blood thinners, vitamin A derivatives and blood pressure medications), as well as stopping hormonal medications such as the birth control pill.
• Long-term conditions: Thyroid diseases, iron deficiency and some long-lasting illnesses may also be linked to this type of shedding.

If you suspect that a medication is causing the shedding, do not stop taking it on your own; talk to the doctor who prescribed it. Sometimes several triggers are present at once, and sometimes no clear trigger can be found.

Hair loss that starts within days or weeks after certain treatments, such as chemotherapy, is a different condition (anagen effluvium: the shedding of hairs that are in the growth phase).

What is the difference between acute and chronic telogen effluvium?

Telogen effluvium is often a limited period of shedding linked to a single trigger; this is called acute telogen effluvium. When the shedding lasts longer than six months, it is called chronic telogen effluvium.

In the acute form, once the trigger is gone, the shedding often decreases within a few months. It takes longer, often several months, for the hair to return to its former fullness. Because hair grows about one centimeter a month, it can take longer to notice the recovery in long hair.

In the chronic form, the doctor checks whether something is keeping the shedding going, such as a thyroid problem, iron deficiency, poor nutrition or a medication taken regularly. Chronic telogen effluvium can be confused with early female pattern hair loss, and the two conditions can also occur together. The doctor tells them apart through an examination and, when needed, further tests.

When should you see a doctor, and which tests are needed?

If the shedding started a few months after a clear trigger and has begun to ease, extensive tests are often not needed. Even so, we recommend that you talk to a doctor rather than guess the cause yourself. It is especially important to see a dermatologist if:

• The shedding lasts longer than six months or is not decreasing
• Your hair is falling out in patches, or a bare spot is forming in a particular area
• You have itching, redness, flaking or pain on your scalp
• Your part is getting wider, or your hairs are gradually getting thinner
• Other symptoms come with it, such as tiredness, weight changes or irregular periods
• You cannot find a clear reason for the shedding

The diagnosis is often made through a detailed conversation and an examination. The doctor looks at your scalp and may do a pull test (gently pulling on a small bunch of hair and checking the hairs that come out easily) and use trichoscopy (examining the scalp with a magnifying device) to look at the thickness of the hairs and at short, newly growing hairs.

If the cause is unclear or the shedding goes on for a long time, blood tests may be requested. These often include a complete blood count, ferritin, which shows the body’s iron stores, and thyroid tests; other tests may be added depending on your symptoms. If you take a supplement that contains biotin, tell your doctor, because it can affect some test results. In some cases where conditions are hard to tell apart, a small tissue sample (biopsy) may need to be taken from the scalp. We also explain when shedding is no longer considered normal in our article on when hair loss is not normal.

What do we not know yet?

• Why doesn’t everyone react the same way to the same trigger? After an illness with a fever or after giving birth, some people have noticeable shedding while others have none at all. The reason for this difference is not fully known.
• How does stress affect the follicle? What we know about stress hormones and nerve signals affecting the follicle’s cycle comes largely from animal studies; the details of this effect in humans are not yet clear.
• At what level does iron matter? Studies on the link between iron deficiency and shedding have produced different results. There is also no agreement on the ferritin level below which it starts to contribute to shedding.
• Can recovery be sped up? There is no medication specifically for telogen effluvium whose effect has been well proven. The main approach is to find and correct the trigger, if there is one, and to give the hair time to recover on its own. In some cases, an additional treatment may be considered; this decision is made after your doctor’s assessment, so do not start taking any medication on your own. There is also no strong evidence that vitamin supplements shorten the shedding when there is no deficiency; you can find the details in our article on hair vitamins and biotin.
• Do PRP or mesotherapy help? These supporting procedures are not an established treatment for telogen effluvium. Most of the research on them is about genetic hair loss; whether they offer any benefit in telogen effluvium is not known.

How does telogen effluvium affect hair transplant planning?

Telogen effluvium is not a condition that a hair transplant can fix. Because the follicles stay in place, the hair lost in this type of shedding often grows back on its own. A hair transplant, on the other hand, works by moving hair follicles that we take from the back and sides of the head, that is, the donor area, which is relatively less affected by genetic hair loss, to areas that have thinned or become bare.

It would not be right to plan a transplant while heavy shedding is still going on, either. Because telogen effluvium affects the whole head, the donor area may also look sparse during this time. At that point, we cannot properly assess either the true density of your hair or what your donor area can provide. That is why we recommend postponing the transplant until the shedding has settled down and its cause has been clarified.

Telogen effluvium sometimes makes existing genetic hair loss more visible. If thinning remains in certain areas after the shedding has settled down, we can discuss the option of a transplant during an examination at that point.

The shock loss that can happen in the weeks after a hair transplant is explained by a similar shift in the cycle; the difference is that it is often limited to the transplanted area and the area around it. We cover this topic in our article on shock loss.

How do we take telogen effluvium into account during the examination?

When you come to us with hair loss, we first talk about when the shedding started and whether, in the few months before, there was a trigger such as an illness with a fever, giving birth, a strict diet or a new medication.

Then we look not only at the thinning area but at your whole scalp, including the donor area. Differences in thickness between hairs, whether the shedding is widespread or limited to certain areas, and the condition of your scalp all guide us.

If we suspect telogen effluvium or another condition that is unrelated to hair transplantation, we recommend that you see a dermatologist. We do not diagnose online, and photos are not enough for this diagnosis. Whether you are suitable for a hair transplant is determined during the examination, and results vary from person to person.