Relieving cough and other symptoms such as runny nose and sneezing due to colds, upper respiratory infections, and allergies. It may also be used for other conditions as determined by your doctor. Coricidin HBP Cough/Cold is an antihistamine and cough suppressant combination. It works by blocking the action of histamine, which reduces allergy symptoms such as watery eyes and sneezing. The cough suppressant works in the brain to help decrease the cough reflex.