Deciduous teeth (milk teeth) usually
begin to appear at about 6 months of
age. All 20 deciduous teeth have usually
erupted by 3 years (see teething).
Permanent teeth(also known as sec-
ondary teeth) usually begin to appear at
about 6 years of age. The first perma-
nent molars erupt towards the back of
the mouth and appear in addition to
the deciduous teeth. The eruption of
permanent teeth nearer the front of the
mouth is preceded by reabsorption of
the roots of the deciduous teeth, which
become loose and detach. Eventually,
permanent teeth replace all the decidu-
ous ones. Wisdom teeth (the backmost,
or 3rd, molars) usually erupt between
ages 17 and 21, but, in some people,
they never appear.
erysipelasAn infection, producing in-
flammationand blistering of the face,
that is associated with a high fever and
malaise. Caused by a streptococcal infec-
tion, erysipelas most often affects young
children and the elderly. Treatment is
with penicillin drugs. (See also cellulitis.)
erythemaA term that means redness
of the skin. Disorders in which skin red-
ness is one feature include erythema
multiforme, erythema nodosum, erythe-
ma ab igne, lupus erythematosus, and
erythema infectiosum (also known as
fifth disease). Erythema can have many
causes, including blushing, hot flushes,
sunburn, and inflammatory, infective, or
allergic skin conditions such as acne,
dermatitis, eczema, erysipelas, rosacea,
and urticaria.
erythema ab igneRed, mottled skin
that may also be dry and itchy, caused
by exposure to strong direct heat, such
as when sitting too close to a fire. The
condition is most common in elderly
women. Dryness and itching can often
be relieved by an emollient. The redness
fades in time but may not disappear.
erythema infectiosumSee fifth dis-
ease.
erythema multiformeAcute inflam-
mationof the skin, and sometimes of
the mucous membranes. The disease
can occur as a reaction to certain drugs,
or may accompany viral infections such
as herpes simplexor bacterial infections
such as streptococcal infections. Other
possible causes are pregnancy, vaccina-
tion, and radiotherapy. Half of all cases
occur for no apparent reason.
A symmetrical rash of red, often itchy
spots erupts on the limbs and some-
times on the face and the rest of the
body. The spots may blister or form
raised, pale-centred weals, called target
lesions. Those affected may have a
fever, sore throat, headache, and/or
diarrhoea. In a severe form of erythema
multiforme, known as Stevens–Johnson
syndrome, the mucous membranes of
the mouth, eyes, and genitals are affect-
ed and become ulcerated.
Corticosteroid drugsmay be given to
reduce the inflammation. People with
Stevens–Johnson syndrome are also
given analgesic drugsand may need
intensive care.
erythema nodosumA condition char-
acterized by the eruption of red-purple,
tender swellings on the legs.
The most common cause is a strepto-
coccal infectionof the throat, but the
condition is also associated with other
diseases, mainly tuberculosisand sar-
coidosis, and may occur as a reaction to
drugs, particularly sulphonamide drugs,
penicillin drugs, and salicylate drugs.
Sometimes there is no apparent cause.
Treatment of any underlying condition
clears the swellings. Bed rest, anal-
gesics, and, occasionally, corticosteroid
drugsmay be necessary.
erythrasmaA skin infection, caused by
CORYNEBACTERIUM, that affects the groin,
armpits, and the skin between the toes.
Raised, irregularly shaped, discoloured
patches appear in the affected areas.
Erythrasma is more common in people
with diabetes mellitus. It usually clears
up when treated with erythromycin.
erythrocyteAnother name for a red
blood cell (see blood cells).
erythrodermaSee exfoliative dermati-
tis.
erythromycinAn antibiotic drugused
to treat infections of the skin, chest,
throat, and ears. Erythromycin is useful
in the treatment of pertussisand legion-
naires’ disease. Adverse effects include
nausea, diarrhoea, and an itchy rash.
escharA scabon the surface of the skin
formed to cover tissue damage.ERYSIPELAS ESCHAR
E