Carbon monoxide is a colorless, odorless, poisonous gas that causes vague f
lulike symptoms which are often misinterpreted by both patients and physici
ans. Fortunately, its slow action allows time for diagnosis and appropriate
intervention. Patients who present with flulike symptoms, especially durin
g the winter, should be questioned regarding risk factors (ie, gas furnace)
that may warrant testing for carbon monoxide poisoning. The mainstays of t
reatment an the liberal use of 100% oxygen therapy and attention to potenti
al poisoning of housemates. The use of hyperbaric oxygen is encouraged in s
erious poisonings (eg, patients with syncope), but definitive indications f
or this therapy await further controlled clinical trials.