cheilitisInflammation, cracking, and dry-
ness of the lips that may be caused by
ill-fitting dentures, a local infection, aller-
gy to cosmetics, excessive sunbathing,
or deficiency of riboflavin (vitamin B 3 ).
chelating agentsChemicals used in
the treatment of metal poisoning that
act by combining with metals such as
lead, arsenic, and mercury to form less
poisonous substances. Penicillamineis
a commonly used chelating agent.
chemistAnother term for a pharmacist.
chemotherapyThe term that usually
describes the use of drugs to treat can-
cerbut which may also describe the use
of antibioticsto treat infectious diseases.
Chemotherapy works by destroying bac-
teria or cancer cells or by preventing
them from multiplying. Cancer chemo-
therapy drugs may also have effects on
normal tissue such as bone marrow,
the intestinal lining, the hair follicles, the
ovaries and testes, and the mouth,
sometimes causing severe side effects.
chenodeoxycholic acidA chemical in
bilethat reduces the amount of choles-
terolreleased by the liverinto the bile.
It is sometimes used to treat small gall-
stones, if they contain mainly cholesterol
and no calcium. Side effects include
diarrhoea and, rarely, liver damage.
chestThe upper part of the trunk.
Known technically as the thorax, the
chest extends from the base of the neck
down to the diaphragm.
chest compressionAlso called cardiac
compression massage (see cardiopul-
monary resuscitation).
chest painPain in the chest, which is
often without serious cause, but which
may be a symptom of an underlying dis-
order requiring urgent treatment. The
pain may be in the chest wall or in an
organ within the chest. The most com-
mon causes of pain in the chest wall are
a strained muscle or an injury, such as
a broken rib. A sharp pain that travels
to the front of the chest may be due to
pressure on a nerve root attached to the
spinal cord as a result of, for example,
osteoarthritisof the vertebrae. Pain in
the side of the chest may be due to
pleurodynia. The viral infection herpes
zoster(shingles) may cause severe pain
along the course of a nerve in the chestinsects commonly called cone-nosed or
assassin bugs. The parasiteslive in the
bloodstream and can affect the heart,
intestines, and nervous system. Symp-
toms include swelling of the lymph nodes
and fever. Long-term complications in-
clude damage to the heart. The drug
nifurtimox kills the parasites in the
blood but has unpleasant side effects.
chalazionA round, painless swelling in
the upper or lower eyelid caused by
obstruction of one of the meibomian
glands that lubricate the edge of the
eyelids. Chalazions are sometimes called
meibomian cysts.They are particularly
common in people suffering from acne,
rosacea,or seborrhoeic dermatitis. If the
cyst becomes infected the eyelid becomes
more swollen, red, and painful. A large
swelling putting pressure on the cornea
at the front of the eye can cause blurring
of vision. About a 3rd of chalazions dis-
appear without treatment, but large
cysts may need to be removed surgically.
chancre, hardAn ulcer, usually on the
genitals, that develops during the first
stage of syphilis.
chancroidA sexually transmitted disease,
found mainly in the tropics, character-
ized by painful ulcerson the genitals
and enlarged lymph nodes in the groin.
The disorder is caused by the bacterium
HAEMOPHILUS DUCREYI. Prompt treatment
with antibiotic drugsis usually effective.
chapped skinSore, cracked, rough skin,
usually on the hands, face, and particu-
larly the lips, due to dryness. Chapping
is caused by the lack, or removal, of the
natural oils that keep skin supple. It tends
to occur in cold weather, when oil-secret-
ing glands produce less oil, or after
repeated washing or wetting. Treatment
is with a lanolin-based cream.
charcoalA form of carbon used in
medicine mainly as an adsorbent agent
in the emergency treatment of some
types of poisoning and drug overdose.
Charcot–Marie–Tooth diseaseAn in-
herited muscle-wasting disease of the
legs (see peroneal muscular atrophy).
Charcot’s jointA joint that is repeated-
ly damaged by injuries that have gone
unnoticed because of loss of sensation
in the joint (see neuropathic joint).
check-upSee examination, physical.
CHALAZION CHEST PAIN
C