We studied substance P (SP)-induced cough in normal subjects without and with colds, and the effects of orally administered procaterol on SP-induced cough in normal subjects with colds. SP aerosols caused cough at a concentration of approximately 10(-15) M in subjects with colds whereas it did not cause cough at a concentration of up to 10(-5) M in subjects without colds. Procaterol (50 micrograms) completely inhibited SP-induced cough in normal subjects with colds. These results suggest that cough response to SP remarkably increases during colds and that beta-2 stimulant may be a useful tool for treatment of cough during colds in normal subjects.