Chlorpheniramine and pyrilamine are antihistamines that reduce the effects of natural chemical histamine in the body. Histamine can produce symptoms of sneezing, itching, watery eyes, and runny nose. Phenylephrine is a decongestant that shrinks blood vessels in the nasal passages. Dilated blood vessels can cause nasal congestion (stuffy nose). The combination of chlorpheniramine, phenylephrine, and pyrilamine is used to treat runny or stuffy nose, sneezing, itching, watery eyes, and sinus congestion caused by allergies, the common cold, or the flu. Chlorpheniramine, phenylephrine, and pyrilamine may also be used for purposes not listed in this medication guide.