In the wide spectrum of medical practice, rhinitis is often incorrectly assumed 
to be solely allergic in etiology. Consequently, other rhinitis subtypes 
(nonallergic and mixed) remain under-diagnosed. This is of concern because 
inaccurate diagnosis may lead to unsatisfactory treatment outcome. Contributing 
to this under-diagnosis is the fact that primary care practitioners do not often 
have at their disposal the same diagnostic tools as the allergist. Tools that 
the allergist is more likely to use include nasal cytology, skin testing and in 
vitro assays for specific immunoglobulin E. Patients with pure nonallergic 
rhinitis have negative skin tests or clinically irrelevant positive results. 
Mixed rhinitis refers to the presence of both allergic and nonallergic rhinitis 
components within the same individual. Allergic rhinitis more commonly develops 
before the age of 20, whereas nonallergic rhinitis affects an older population 
and disproportionately more females. The type of nasal symptoms manifested by 
the patient usually does not differentiate allergic from nonallergic rhinitis. 
Vasomotor rhinitis is the most common form of nonallergic rhinitis, followed by 
nonallergic rhinitis with eosinophilia and others. In terms of estimated 
prevalence, allergic rhinitis affects approximately 58 million Americans, 19 
million have pure nonallergic rhinitis and 26 million have mixed rhinitis. Thus 
a wide spectrum of relevant epidemiologic information can be used to assist in 
determining the differential diagnosis of rhinitis. Physicians are reminded to 
look further and consider whether a rhinitis patient truly has pure allergic 
rhinitis or whether a diagnosis of mixed rhinitis or nonallergic rhinitis is 
more appropriate.