Telogen effluvium (sudden hair loss): what it is and how to recognize it

Telogen effluvium is the diffuse and abundant loss of hair in the months following a stressor. It is a common, non-scarring cause of hair loss in which approximately 20% or more of the hairs that were in the anagen phase (growth and development phase) abruptly switch to the telogen phase (quiescence phase) with subsequent subsequent hair loss and loss of hair density if it continues.

Each follicle goes through different phases throughout its life, three are the main ones, although others have been described that are of interest for scientific studies.

1. Anagen phase: this is the longest phase, from 2-3 to 6 years sometimes. It is the development and growth phase. 85-90% of follicles are in this phase.
2. Catagen phase: is very short, lasting about 2-3 weeks. It is a phase of involution and pause. Very few follicles are in this phase (1-2%).
3. Telogen phase: intermediate duration of 3-6 months. Falling and renewal phase. Approximately 10-15% of follicles are in this phase.

These phases are asynchronous with each other, i.e. they are not synchronized. They occur in a disorderly manner over time, which is why we do not go completely bald and our hair is renewed daily without realizing it.

A healthy scalp is born with approximately 90,000 – 100,000 follicular units, which can contain between 1-4 hairs. If 10% of these are in the telogen (shedding) phase in a normal way, this means that 80-100 hairs can fall out daily. So if a person has more hair, more hair will fall out daily.

If, for whatever reason or situation, a person is suffering from acute telogen effluvium, he or she may lose between 150-200 hairs per day, a situation that is especially noticeable in dark-haired women, since their hair is longer and darker.

Hair loss during effluvium is painless and painless. It should be mentioned that sometimes it is associated with trichodynia, a burning and/or painful sensation of the scalp that several studies have shown to be associated with an increase in substance P, a neuropeptide involved in the perception of pain, and increased in effluvium situations.

Why does telogen effluvium occur?

During a person’s life there are events or situations that produce a stressful situation, nutritional deficits or hormonal alterations that are detected by the hair follicles, causing them to enter a preventive phase (to avoid damage) of pause-involution and subsequent telogen-fall.

Some of these triggering factors of effluvium (“triggers”) are:

• Systemic diseases and infections (e.g., COVID-19, HIV, malaria, tuberculosis, hypothyroidism).
• Stressful events (e.g., depression, job layoff, pandemic).
• Drugs (e.g., beta-blockers, anticoagulants, anticonvulsants).
• Nutritional deficiencies (e.g. iron deficiency anemia, vitamin B12, folic acid deficiencies).
• Major surgery (e.g. intestinal tumor resection, internal organ transplantation).

The literature has reported the association between acute telogen effluvium and dengue, human immunodeficiency virus (HIV) infection, influenza, typhoid fever, scarlet fever, pneumonia, pertussis, tuberculosis and malaria, and currently COVID-19.

Although circumstances of high stressful level for the organism have been described, each individual has a different susceptibility, just as a cardiac transplant for one patient would not imply the appearance of effluvium, for another person a job layoff, change of city or partner could result in an intense effluvium.

Is there Telogen Effluvium after COVID-19?

Indeed, more intense post-COVID effluvium episodes than usual and of longer duration have been described, “cytokine storm” and “systemic hyperinflammatory syndrome” are the most proposed causes responsible for follicular damage in post-COVID-19 Telogen Effluvium. Other theories include altered coagulation and microthrombus formation and/or direct damage to the follicle caused by the virus itself.

Non-definitive hair loss: the hair may continue to grow.

Acute telogen effluvium occurs approximately 3-6 months after the trigger and usually resolves within 6 months of onset, however if the situation persists and continues beyond 6 months it is called chronic telogen effluvium, this is more common in women aged 30-60 years, does not appear to have any racial predilection and in about 33% of cases the cause remains unknown.

You will not go bald, you may lose density. Yes, by definition an effluvium is a type of non-scarring alopecia, i.e. the follicular unit (although without hair, or with fewer stems per unit) is still intact so that after the passage or resolution of the trigger or correction of alterations in case there were any, the hair begins to regrow. It can take from 6 to 24 months for a complete recovery of the previous capillary state.

Steps to follow and treatment

1. An adequate clinical history that recognizes the trigger/s.
2. A physical and trichoscopic examination to rule out other pathologies (especially scarring alopecia).
3. Perform tests if necessary (e.g. a blood test).
4. Once the diagnosis is confirmed, correct the triggering causes (e.g. vitamin or iron supplements, drugs for hypothyroidism, correct anemia, eliminate or change causative drugs).
5. If necessary add topical or oral treatment (e.g. minoxidil, finasteride, ketoconazole). This depends on other pathologies or examination findings and it is up to the physician to prescribe them.
6. Associate in-clinic treatments such as hair biostimulation mesotherapy with Platelet Rich Plasma or autologous micro-grafting technology with Regenera© technology.
7. Adequate control and follow-up.

If there is no specific cause or to be corrected, doing nothing and waiting is an option, after all it is a type of non-scarring alopecia that in most cases self-limits and recovers spontaneously. Keeping calm and having an adequate follow-up are the key to this pathology.