Patients with
multiple chemical sensitivity and
eczema patients with airway symptoms elicited by odorous chemicals have enhanced
cough reflex to
capsaicin when applying the tidal breathing method. The aims of the present study were to test whether the
capsaicin induced
cough reflex was enhanced when applying the single breath inhalation method in similar groups of patients with symptoms related to odorous chemicals e.g. other persons wearing of
perfume; and to investigate to what extent the reporting of lower airway symptoms influenced the
cough reflex. Sixteen patients fulfilling Cullen's criteria for
multiple chemical sensitivity and 15
eczema patients with airway symptoms elicited by odorous chemicals were compared with 29 age-matched, healthy controls. We measured C5--the
capsaicin concentration causing five
coughs or more--using the single breath inhalation test. No difference was found between groups in age, body mass index or pulmonary function. The median C5 were 129 micromol/L (control group), 48 micromol/L (
multiple chemical sensitivity patients), 32 micromol/L (
eczema patients). The reporting of lower airway symptoms from odorous chemicals was significantly (p<0.05) correlated to increased
cough reflex sensitivity to
capsaicin, independent of patient group or co-existence of
asthma. The results suggest that the C5 is not reliable for diagnosing MCS but C5 can be used to verify presence of lower airway symptoms related to odorous chemicals.