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Cough results from forced expulsion, usually against a closed glottis, creating a characteristic sound. It is a natural reflex and defense mechanism that helps the body clear excessive secretions and prevents foreign material from entering the respiratory tract. At times, cough can become excessive, nonproductive, disturbing to the patient, and potentially harmful. Cough is a complex symptom and often requires a multidisciplinary approach to ascertain its cause and effective treatment. Evaluation should be guided by a thorough history and physical examination, and testing should be individualized for cost effectiveness. Habit cough and unexplained cough are diagnoses of exclusion, and any tendency to underdiagnose or overdiagnose these conditions should be avoided. Most over-the-counter cough suppressants are not as effective as previously thought, and their use in routine practice should be minimized. Future research should be conducted to elucidate the mechanisms of cough production and to develop cough-suppressive pharmacotherapy. Allergists, as experts in the management of upper and lower airway disorders, should play a central role in the diagnosis and management of cough.

Background The number of allergy skin tests required to evaluate patients with respiratory allergy has recently been challenged by the managed care community. Objectives The purpose of this study was to determine which aeroallergens are prevalent in patients with respiratory allergy (allergic rhinitis and bronchial asthma) in California. Methods Utilizing aeroallergens thought to be relevant from recent aerobiologic and botanic data, 141 allergic and 17 asymptomatic control subjects were tesetd for the prevalence of 103 allregens. A standardized prick puncture technique and standardized interpretation of wheal/flare responses were utilized using the same lot of allergen for 13 allergy practices distributed throughout California. Frequency curves based on prevalence were established to determine the number of tests required to give up to 90% of positive responses for tree, weed and grass pollen mold spores, and miscellaneous allergens which included house dust mite, cat, dog, and cockroach allergens. Results Positive responses in allergic subjects for grasses ranged from 46% to 54%, for weeds 19% to 37%, and for trees 10% to 42%. For molds the range was 11% to 22%. The response rate for Dermatophagoides pteronyssinus was 53%, for Dermatophagoides farinae 42%, for cat pelt 39% and cat hair 37%, for cockroach 23% and dog dander 19%. Asymptomatic control subjects responded to only 4% of all allergens tested. Ninety percent of all positive tests required three miscellaneous allergens (house dust mite, cat, and cockroach), 9 molds, 2 grasses, 16 weeds, and 27 trees for a total of 57 allergens (56% of total tested). There was no clear relationship between locale and specific allergen response, probably related to the limited number of subjects tested and variability within the same geographic region. Several seldom tested tree and weed allergens showed a higher prevalence rate than several commonly tested for allergens. Conclusions This preliminary study suggests that approximately 57 aeroallergens might be adequate to detect 90% of all positive responses in patients with respiratory allergy in California. This study was limited by subject number and variability between study sites. It is hoped a standardized model can be developed from this pilot study to definitively determine which aeroallergens are relevant in the United States.