Demystifying science | When stress causes hair to fall out

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Yes, it can happen.

A phenomenon called “telogen effluvium”, a premature loss of a significant part of the hair, occurs in episodes of significant biological stress. This can include considerable weight loss, particularly if accompanied by nutrient deficiencies.

Hormonal changes, such as miscarriage, puberty or menopause, can cause telogen effluvium. Infectious diseases too.

“Telogen effluvium is probably the most common form of hair loss,” says Wilma Bergfeld, a dermatologist at the prestigious Cleveland Clinic, who is responsible for the section on this subject in the medical encyclopedia Up to Date from the Dutch publisher Wolters Kluwer.

Hair loss generally occurs two to four months after the stressor, specifies the D^D Bergfeld. It can therefore occur a few months after significant weight loss.

The hair cycle follows three phases: growth, for a few years, a buffer phase for a few weeks, and finally, hair loss, caused by hair detachment from the scalp because other hairs are growing underneath. This last phase, called “telogen”, lasts two to three months, and usually, 15% of the hair is in this phase.

Telogen effluvium causes up to 20% to 30% hair loss, according to D^D Bergfeld. “The hair is finer, and you collect a lot of hair when you comb your hair. »

Because hair grows at a rate of one to two centimeters per month, it takes several months for hair volume to recover, she says. Hair is one of the fastest growing cells in the human body.

Find the cause

When a patient consults the D^D Bergfeld with a problem like this, the first step is to see if a stressful event has occurred in the previous six months. “It could be a reaction to a new medication, or an underlying illness. It is important to exclude these causes. »

COVID-19 has caused many cases of telogen effluvium, observes the D^D Bergfeld.

If hair loss is linked to weight loss, it may be helpful to check for dietary deficiencies, the Ohio dermatologist points out.

Hereditary hair loss from the twenties, often on the crown of the head, is completely independent of telogen effluvium and does not aggravate it.

If hair takes more than a few months to grow back, you can use minoxidil, a blood pressure medication from the 1970s that has been shown to help hair growth, says Dr.^D Bergfeld. It is also known as Rogaine. A low-dose oral version has been introduced and appears safe and easier to use than the topical version, she adds.

Marie-Ève ​​Pinet, a dermatologist from Quebec to whom the Canadian Dermatology Association referred The Pressalso prescribes minoxidil against telogen effluvium.

“Minoxidil can take at least six months before demonstrating real effectiveness,” she warns. It may therefore be useful to wait before using it if the hair loss is still very recent. Also, many people fear losing their hair again if they stop treatment. But hair only starts to fall out again if the cause of hair loss is still active. »

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