Some hair loss conditions go by the name "effluvium," which means an
outflow. Effluviums characteristically affect different phases of the hair
Hair follicles on the scalp do not continuously produce hair. They cycle
through a growth stage that can last two or more years, then regress to a
resting stage for up to two months before starting to grow a new hair fiber
again. At any time on a healthy human scalp, about 80% to 90% of the hair
follicles are growing hair. These active follicles are in what is called the
anagen phase. That leaves up to 10% to 20% percent of scalp hair follicles in a
resting state called telogen, when they don't produce any hair fiber.
Telogen effluvium (TE) is probably the second most common
form of hair loss dermatologists see. It is a poorly defined condition; very
little research has been done to understand TE. In essence though, TE happens
when there is a change in the number of hair follicles growing hair. If the
number of hair follicles producing hair drops significantly for any reason
during the resting, or telogen phase, there will be a significant increase in
dormant, telogen stage hair follicles. The result is shedding, or TE hair
TE appears as a diffuse thinning of hair on the scalp, which may not be even
all over. It can be a bit more severe in some areas of the scalp than others.
Most often, the hair on top of the scalp thins more than it does at the sides
and back of the scalp. There is usually no hair line recession, except in a few
rare chronic cases.
The shed hairs are typically telogen hairs, which can be recognized by a
small bulb of keratin on the root end. Whether the keratinized lump is
pigmented or unpigmented makes no difference; the hair fibers are still typical
People with TE never completely lose all their scalp hair, but the hair can
be noticeably thin in severe cases. While TE is often limited to the scalp, in
more serious cases TE can affect other areas, like the eyebrows or pubic
Whatever form of hair loss TE takes, it is fully reversible. The hair
follicles are not permanently or irreversibly affected; there are just more
hair follicles in a resting state than there should normally be.
There are three basic ways TE can develop.
1. There might be an environmental insult that "shocks" the growing hair
follicles so much that they decide to go into a resting state for a while. This
results in an increase in hair shedding and a diffuse thinning of hair on the
scalp. This form of TE can develop rapidly and may be noticeable one or two
months after receiving the shock. If the trigger is short lived, then the hair
follicles will return to their growing state and start producing new hair
fibers pretty quickly. This form of TE usually lasts less than six months and
the affected individual has a normal scalp hair density again within a