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