Allergic rhinitis and nonallergic rhinitis (NAR) are prevalent diseases that have been linked to an increased risk of obstructive sleep apnea (OSA). The purpose of this review is to offer a better understanding of the connection between these diseases by summarizing the potential underlying pathophysiological processes. In adults, allergic rhinitis and NAR can be seen as potentiating symptoms instead of as potentiating risk factors in the fields of OSA pathophysiology, while in children they are seen as the first-line therapy recommended for children with OSA, independent sleep-disorders (SDB) predictors and the absence of adenotonsillectomy. Recent research indicates that IL-6 may have a role in regulating the sleep–wake cycle, and that serum soluble IL-6 receptor (sIL-6R) levels may reflect the severity of OSA. Elevated Th17/Treg ratio correlates favorably with OSA patients’ apnea–hypopnea index, and Th17 and Treg imbalances induced by allergic rhinitis and OSA, respectively, may likely encourage each other, leading to greater imbalance. Furthermore, obesity is a significant risk factor for OSA, because leptin is involved in ventilatory function and upper airway blockage. The nasal trigeminal reflex and the variant trigeminocardiac reflex may potentially be implicated in the relationship between rhinitis and OSA.
OSA and allergic rhinitis/NAR are intimately linked, and either can be harmful to the other. As a result, doctors should be aware of the possibility of allergic rhinitis/NAR in OSA patients, as well as vice versa.