Encyclopedia of Health and Medicine

D
dandruff A common symptom in which the
sebaceous glands on the scalp increase their activity,
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 accumulate
on the scalp’s surface (most commonly on
the top of the head) or flaking that may appear in
the HAIR and on the clothing. BACTERIA and yeast
(FUNGUS) normally present on the skin can irritate
and inflame the sebaceous structures of the scalp,
a condition doctors call seborrheic DERMATITIS. Dermatologists
often diagnose seborrheic dermatitis as
the underlying cause of dandruff. PSORIASIS and
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 dandruff
and requires a doctor’s evaluation.
Though numerous factors may contribute to
dandruff, dermatologists believe a convergence of
genetics, age, hormones, and environmental conditions
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 characterized
by hormonal surges. Dandruff also
becomes more common during times of physical
or emotional stress, and when external environmental
conditions are cold and dry such as is typical
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
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are the key symptoms of dandruff. The scalp
sometimes itches. The diagnostic path includes
examination of the skin over all of the body to distinguish
simple dry skin, which can cause flaking,
from dandruff, as well as to rule out other dermatologic
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 rinsing.
Moderate dandruff—obvious flakes in the
hair and on the shoulders—may require shampooing
with products that contain ingredients to
curtail the growth of keratinocytes, the cells that
make up most of the skin’s outer layer (epidermis).
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 prescription
shampoos or lotions that often contain
stronger concentrations of the active ingredients
that over-the-counter products contain. For very
severe dandruff with INFLAMMATION of 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