In one visit patients will be characterized with a questionnaire based on the ISAAC questionnaire. Furthermore, FeNO, eCO, skin prick testing and total serum IgE will be examined. The psychiatric condition of patients will be determined by CBCL/6-18 and YSR/11-18 behavior questionnaires. After initial fiberoptic laryngoscopy and pulmonary function testing, bronchoprovocation is performed using nebulized methacholine at increasing doses, until a 20% decline in the forced expiratory volume in 1 second is achieved (PD20FEV1). Each methacholine testing will be followed by a second laryngoscopy and pulmonary function testing. The visualization of paradoxical vocal cord motion during inspiration will be recorded.