Telogen Effluvium

Telogen effluvium is diffuse shedding that happens when a large number of follicles enter their resting phase at once, usually a few months after illness, surgery, stress or a nutritional problem.

Where you'll meet it

When hair comes out in handfuls over weeks, all over the scalp rather than in a pattern, often two to four months after something significant happened to your body. More hair in the plughole, more on the pillow, a ponytail that feels thinner. It is frightening, and it is usually not what it looks like.

What is actually happening?

At any time, most of your follicles are growing and a minority are resting. Telogen is the resting phase, and at its end the old hair falls out to make way for a new one. A shock to the body can push a large share of follicles into telogen at the same time. A couple of months later, they all shed together.

The delay is what confuses people. By the time the hair falls out, the trigger is often in the past and forgotten, so the shedding seems to come from nowhere.

What triggers it?

Major illness or high fever, surgery under general anaesthetic, childbirth, crash dieting or significant weight loss, iron deficiency, thyroid disease, severe psychological stress, and starting or stopping some medications. Starting minoxidil or finasteride can cause a short shed of its own, which works on the same principle and settles.

How is it different from pattern loss?

Telogen effluvium is diffuse, sudden and usually temporary. Androgenetic alopecia is patterned, gradual and progressive. Telogen effluvium thins the whole scalp, including the back and sides; pattern loss spares them. Under magnification, pattern loss shows a mix of thick and thin hairs, while telogen effluvium shows normal-calibre hairs, just fewer of them.

The two can overlap, and a bout of shedding can unmask pattern loss that was already quietly happening. That is one reason a dermatologist's diagnosis is worth more than a self-diagnosis from photographs.

Does it recover?

Usually, yes. Once the trigger has passed or been treated, shedding typically slows over a few months and regrowth fills in over six to twelve. Hair grows slowly, so it can take a year to look normal again. When shedding keeps going for more than six months, it is called chronic telogen effluvium and needs a proper medical look for an ongoing cause.

What should you do?

See a doctor and get ferritin and thyroid checked, along with anything else they think relevant. Finding a treatable cause is worth more than any product, and it costs a blood test. Blocking DHT does nothing for telogen effluvium, so buying hair loss drugs for it mostly wastes time.

Why does it matter for a transplant?

Because a transplant into an actively shedding scalp is a bad idea. Diffuse shedding can also thin the donor area temporarily, making any assessment of your supply unreliable until it settles. A good clinic will ask why you are shedding before talking about surgery. Start Here explains why diagnosis comes first.

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