Medically reviewed by Dr. A.M. van Coevorden, dermatologist
Telogen effluviumtemporary, diffuse hair loss after a disruption of the hair cycle
Telogen effluvium is temporary, excessive hair loss caused by a disruption of the hair growth cycle, in which the hair thins diffusely without real bald patches. Often an event precedes it, such as childbirth, illness or surgery, and the shedding usually only becomes noticeable months later. It recovers on its own in most cases.
What is telogen hair loss?
Telogen hair loss is excessive shedding of hairs caused by a disruption of the hair growth cycle.
The hair growth cycle
Hairs grow in follicles; the scalp has about 100,000 at birth. Each follicle repeatedly goes through a cycle of three phases: the anagen growth phase (about three years), the short catagen transition phase, and the telogen resting phase averaging four months, after which the hair sheds while a new hair has already formed. In an adult about 85 to 90% of scalp hair is in the growth phase, and normally a person loses 50 to 100 scalp hairs a day.
How does telogen hair loss develop?
There is acute and chronic telogen hair loss. In the acute form a triggering event usually precedes it, disrupting the cycle: many hairs move to the resting phase at once and shed more or less together a few months later. Triggers include childbirth (the most common cause), serious illness, high fever, surgery under general anaesthetic, bleeding and severe restriction of food intake. The shedding usually becomes noticeable only two to five months after the event, and in about a third no cause is found. Hair loss lasting longer than six months is called chronic; known causes are thyroid disorders, anaemia from iron deficiency and certain medicines, such as retinoids, blood thinners, beta blockers, thyroid inhibitors and chemotherapy. This form mainly occurs in women between 30 and 50.
What are the symptoms?
The only symptom is hair shedding without real bald areas forming. The loss is most noticeable when combing or washing. Despite sometimes heavy shedding, others often do not see it, because thinning only becomes clearly visible once 20 to 50% of the hair is lost.
Is telogen effluvium contagious?
No. Telogen effluvium is not contagious and does not pass from person to person.
How is the diagnosis made?
The diagnosis can be made with a clear increase in shedding telogen hairs, recognisable by the light club-shaped end at the root. Sometimes the dermatologist does a hair-pull test or examines a tuft of hair under the microscope (trichogram), and occasionally a small piece of skin is removed. The doctor asks about possible causes, and blood tests follow if needed. If a medicine may be the cause, it must be stopped for at least three months before the effect can be judged.
What is the treatment?
Acute telogen hair loss always recovers on its own; there is no treatment to speed this up. There is no treatment for the chronic form either, unless a cause is found and can be resolved. If the hair becomes too thin, temporarily wearing a wig is a good option.
What is the outlook?
The outlook for acute telogen hair loss is excellent: the shedding usually stops within three to six months (at most a year) if the trigger does not recur, after which the hair fully recovers. In chronic telogen hair loss, gradual recovery occurs once the cause is found and treated or removed. In women with no identifiable cause the shedding often fluctuates for years, but spontaneous recovery usually occurs in the end.
Frequently asked questions about telogen effluvium
Will my hair grow back?
Yes, usually. Acute telogen hair loss always recovers on its own, usually within three to six months after the cause has passed.
What causes it?
Often an event a few months earlier, such as childbirth, illness, fever or surgery. The chronic form can be caused by thyroid problems, anaemia or certain medicines.
Why does the shedding start months after the cause?
Because the hairs first go through the resting phase of a few months before shedding. So the loss usually appears two to five months after the event.
Will it make me bald?
No. The hair thins diffusely, but no real bald patches form.
Is there a treatment?
Not for the acute form, which recovers on its own. For the chronic form, treatment targets the underlying cause, such as the thyroid or anaemia.