Comparison of citric acid and mannitol cough provocation tests among subjects with chronic cough and healthy volunteers.

35 subjects with chronic cough plus 25 subjects without any cough will be asked to participate. The study consists of two visits in the outpatient clinic of Kuopio University Hospital, department of respiratory medicine, 2 - 7 days apart. They will fill in the Leicester Cough Questionnaire and undergo two different cough provocation tests, in random order: Mannitol test and citric acid test. If a chest x-ray has not been taken within 6 months, it will be taken.

Inclusion Criteria, Chronic cough patients:

(both criteria must be fulfilled)

• presence of current chronic cough (> 8 weeks)
• Leicester Cough Questionnaire total score < 17

Inclusion criteria, healthy volunteers

• absence of any form of cough

Exclusion Criteria:

• age < 18 years
• any disability which would challenge the subject's ability to understand the purpose and methods of the study
• pregnancy
• breastfeeding
• current smoking or ex smoking more than 10 pack years
• any thoracic x-ray finding indicating urgent mediacal interventions