High nitric oxide is not necessarily due to asthma. In clinical practice, patients with asthma may have elevated exhaled nitric oxide, which is often indicative of eosinophilic airway inflammation. In asthma, eosinophilic airway inflammation is more common, especially when asthma is not controlled, it is more likely to manifest as eosinophilic airway inflammation, resulting in elevated exhaled nitric oxide. Elevated exhaled nitric oxide is not always caused by asthma, but may also be seen in other conditions, such as eosinophilic airway inflammation in some patients with chronic obstructive pulmonary disease, resulting in elevated exhaled nitric oxide. Sometimes patients with chronic eosinophilic bronchitis can also have elevated exhaled nitric oxide. Therefore, high nitric oxide alone is not necessarily a sign of asthma and needs to be analyzed in the context of the patient’s specific clinical symptoms.