In the case of carbon monoxide poisoning, what symptom may be present?

In cases of carbon monoxide poisoning, cherry-red skin is a classic symptom that may indicate the presence of carbon monoxide in the bloodstream. Carbon monoxide binds to hemoglobin more than 200 times more readily than oxygen, forming carboxyhemoglobin. This compromises the oxygen-carrying capacity of the blood and can lead to a characteristic color change in the skin, appearing a rosy or cherry-red hue.

While fever, a cough with sputum, and constricted pupils can occur in various conditions, they are not specific to carbon monoxide poisoning. Fever may be associated with infection or inflammatory processes, a cough with sputum is typically related to respiratory conditions, and constricted pupils can occur in various drug-related situations. Thus, cherry-red skin is a distinctive sign that points specifically to carbon monoxide exposure, making it the most relevant symptom in this context.