OXYMETAZOLINE
OZONE
oxygen in body tissues). The oxygen is
usually delivered through a face-mask or
a nasal cannula (a length of narrow plas-
tic tubing with two prongs that are
inserted into the nostrils). Piped oxygen
is used in hospitals; oxygen in cylinders
can be used at home for acute attacks
of hypoxia, such as those occurring in
severe asthma. Long-term therapy for
people with persistent hypoxia may in-
volve the use of an
oxygen concentrator.
(See also
hyperbaric oxygen treatment.)
oxymetazoline A
decongestant
drug
used in the treatment of
allergic rhinitis
,
sinusitis
, and the common
cold
.
oxytetracycline A tetracycline
antibiotic
drug
that is used to treat
chlamydial in-
fections
such as
nongonococcal urethritis.
It is also used for a variety of other
infective conditions, including
bronchi-
tis
and
pneumonia
; in addition, the drug
may be used to treat severe
acne
.
Side effects may include nausea, vom-
iting, diarrhoea, skin rash, and increased
sensitivity of the skin to sunlight. Oxy-
tetracycline may discolour developing
teeth, and is not given to children under
12
or to pregnant women.
oxytocin A
hormone
produced by the
pituitary gland
. Oxytocin causes uterine
contractions
during labour and stimulates
milk-flow in
breast-feeding
women.
Synthetic oxytocin is used for
induc-
tion of labour
. It is given by intravenous
infusion to produce uterine contractions.
It is also often given with ergotamine as
a single dose after delivery to prompt
placental separation and expulsion, to
reduce blood flow, or to empty the
uterus after an incomplete
miscarriage
or a fetal death. A possible adverse
effect of synthetic oxytocin is abnorm-
ally strong, painful contractions. Rare
side effects include nausea, vomiting,
palpitations, and allergic reactions.
oxyuriasis An
alternative
name
for
enterobiasis or
threadworm infestation
.
ozena A severe and rare form of
rhinitis
,
in which the mucus membrane in the
nose wastes away and a thick nasal dis-
charge dries to form crusts. Ozena often
causes severe
halitosis.
ozone A rare form of oxygen, ozone is a
poisonous, faintly blue gas that is pro-
duced
by
the
action
of
electrical
discharges (such as lightning) on oxy-
gen molecules. Ozone occurs naturally
in the upper atmosphere, where it
screens the Earth from most of the
Sun's harmful ultraviolet radiation. The
ozone layer is being depleted by atmo-
spheric pollutants, allowing increasing
amounts
of ultraviolet radiation
to
reach the Earth's surface. This problem
could lead to a rise in the incidence of
skin cancer
and
cataracts,
as well as hav-
ing other potentially hazardous effects.
O
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