D

dandruff A common symptom in which the
sebaceous glands on the scalp increase their activ-
ity, accelerating the SKIN’s normal, continuous
process of replacing itself. Consequently the skin
on the scalp sheds cells at an accelerated rate,
causing visible patches of collected cells that accu-
mulate on the scalp’s surface (most commonly on
the top of the head) or flaking that may appear in
the HAIRand on the clothing. BACTERIAand yeast
(FUNGUS) normally present on the skin can irritate
and inflame the sebaceous structures of the scalp,
a condition doctors call seborrheic DERMATITIS. Der-
matologists often diagnose seborrheic dermatitis as
the underlying cause of dandruff. PSORIASISand
tinea capitis are also common causes.

Flaky, patchy SKIN on the eyebrows,

around the eyelashes, and other sites on

the body beyond the scalp may signal a

dermatologic condition other than dan-

druff and requires a doctor’s evaluation.

Though numerous factors may contribute to
dandruff, dermatologists believe a convergence of
genetics, age, hormones, and environmental con-
ditions accounts for most cases, as these are the
factors that generally influence sebaceous activity.
Dandruff flare-ups are common during PUBERTY,
PREGNANCY, and MENOPAUSE, periods of life charac-
terized by hormonal surges. Dandruff also
becomes more common during times of physical
or emotional stress, and when external environ-
mental conditions are cold and dry such as is typi-
cal in the winter.

Symptoms and Diagnostic Path

Light-colored patches on the scalp that flake when
scratched or flakes in the hair and on the clothing

are the key symptoms of dandruff. The scalp

sometimes itches. The diagnostic path includes

examination of the skin over all of the body to dis-

tinguish simple dry skin, which can cause flaking,

from dandruff, as well as to rule out other derma-

tologic conditions. The dermatologist may conduct

further testing, such as skin scraping or biopsy,

when there is reason to suspect a condition other

than one that commonly causes dandruff.

Treatment Options and Outlook

Mild dandruff—light, barely noticeable flaking

that remains along the scalp or in the hair—often

clears with daily shampooing and thorough rins-

ing. Moderate dandruff—obvious flakes in the

hair and on the shoulders—may require sham-

pooing with products that contain ingredients to

curtail the growth of keratinocytes, the cells that

make up most of the skin’s outer layer (epider-

mis). Such shampoos typically contain selenium

sulfide, zinc pyrithione, or coal-tar extracts.

Which products are more effective seems a matter

of personal preference.

Severe dandruff—flakes are always present in

the hair and on the clothing—may require pre-

scription shampoos or lotions that often contain

stronger concentrations of the active ingredients

that over-the-counter products contain. For very

severe dandruff with INFLAMMATIONof the skin and

sebaceous structures, the doctor may prescribe

corticosteroid drops or lotion in combination with

other remedies. Stubborn dandruff may require a

regimen of products to bring it under control,

though most people can then keep dandruff in

check with a few core products.

Recent research suggests that many people who

have seborrheic dermatitis, the most common

cause of persistent dandruff, may have a skin

147