 Symptoms of mild acute poisoning include lightheadedness , confusion , headache , vertigo , and flu @-@ like effects ; larger exposures can lead to significant toxicity of the central nervous system and heart , and death . After acute poisoning , long @-@ term sequelae often occur . Carbon monoxide can also have severe effects on the fetus of a pregnant woman . Chronic exposure to low levels of carbon monoxide can lead to depression , confusion , and memory loss . Carbon monoxide mainly causes adverse effects in humans by combining with hemoglobin to form carboxyhemoglobin ( <unk> ) in the blood . This prevents hemoglobin from carrying oxygen to the tissues , effectively reducing the oxygen @-@ carrying capacity of the blood , leading to hypoxia . Additionally , myoglobin and mitochondrial cytochrome oxidase are thought to be adversely affected . Carboxyhemoglobin can revert to hemoglobin , but the recovery takes time because the <unk> complex is fairly stable . 
