What are the symptoms of carbon monoxide poisoning? Unfortunately, the symptoms of carboxyhemoglobin saturation are easily overlooked because they are often flu-like. With mild exposure, most commonly you may experience headaches, fatigue and nausea. Medium exposure can cause a severe throbbing headache, drowsiness, disorientation, confusion and an accelerated heart rate. Extreme exposure can lead to unconsciousness, convulsions, cardiorespiratory failure, coma and possibly death.