The clinical symptoms of perennial laryngeal allergy include a persistent cough, itching and irritation of the throat. We endeavored to shed some light on the features of antigens and laryngeal findings of perennial laryngeal allergy. A clinical study focusing on the diagnosis of laryngeal allergy was carried out in 53 patients exhibiting a persistent cough, itching and irritation of the throat. A diagnosis of laryngeal allergy was confirmed based on the effectiveness of H1-blockers and the presence of specific IgE antibodies by RAST testing. Laryngeal allergy was diagnosed according to the criteria proposed by the Society of Study for Laryngeal Allergy in Japan（2011）.
Seventeen of the 53 patients were diagnosed with perennial laryngeal allergy. A major positive perennial antigen in laryngeal allergy is the house dust mite. In comparison to nasal allergy, moth and cockroach antigens have a higher positive frequency with perennial laryngeal allergy.
The sensitivity and specificity of nasopharyngeal smears for laryngeal allergy were 59% and 73%, respectively. H1-blockers were significantly effective with positive nasopharyngeal smears.
A pale laryngeal mucosa was typical laryngeal feature in perennial laryngeal allergy cases, and patients whom antihistamines were effective tended to exhibit a pale laryngeal mucosa.