Rhinorrhea, commonly known as a runny nose, consists of an unusually significant amount of nasal ischarge. It is a symptom of the common cold and of allergies (hay fever). The term comes from the Greek words "rhinos" meaning "of the nose" and "rhoia" meaning "a flowing." Rhinorrhea can also be a sign of withdrawal, such as from opioids (especially methadone). Symptoms display circadian rhythms.