Poor asthma control?--then look up the nose. The importance of co-morbid rhinitis in patients with asthma.

Many factors can impair asthma control. One which is frequently overlooked is rhinitis. Asthma patients with significant rhinitis are over four times more likely to have poorly controlled asthma than those without. Over 80% of patients with asthma have rhinitis, which may be allergic or inflammatory/non-allergic. Both types of rhinitis share pathophysiological similarities with eosinophilic asthma, cause bronchial hyper-reactivity, and are predisposing factors for the subsequent development of asthma. Nasal allergen challenge in allergic rhinitis results in inflammation in the bronchi as well as the nose, and the reverse is also true. This article reviews briefly the evidence for the link between asthma and rhinitis, advocates looking for rhinitis when patients present with poorly controlled asthma, and provides guidance for the diagnosis and treatment of rhinitis.