Nasal Hyperreactivity: Nonspecific Nasal Provocation Tests. Review by the Rhinoconjunctivitis Committee of the Spanish Society of Allergy and Clinical Immunology.

Nasal hyperreactivity is the abnormal reaction of nasal tissue to a stimulus that is innocuous to most people. This response is caused by dysregulation of the autonomic nervous system at various levels of the nasal autonomic reflex arc. Various stimuli (methacholine, histamine, adenosine 5'-monophosphate, cold air, mannitol, capsaicin, phentolamine, and distilled water) have been used in an attempt to find the test that most reliably differentiates between healthy individuals and patients and also between different types of rhinitis. Despite the small number of publications available, in the present review, we provide an update on current nonspecific nasal provocation techniques. The studies published to date are not comparable: the stimuli applied act through different mechanisms and are used to assess different pathways, and the methodologies differ in terms of selection of participants, concentrations used, and assessment of response (criteria for positivity). Given the limited use of nonspecific nasal provocation tests in routine clinical practice, we believe that more studies are warranted to address the research issues we present at the end of the present review, for example, the need to standardize the methodology for each test or even the clinical benefits of knowing whether or not a patient has nasal hyperreactivity.