A viral infection (the common cold) is the most common cause of a stuffy and/or runny nose, but allergies, influenza, and sinus infections also may cause these symptoms.Less commonly, anatomical obstructions (e.g. a deviated nasal septum, foreign bodies) may lead to nasal congestion.Other causes of a stuffy or runny nose include environmental factors, hormonal changes, and some medications. viral infection (the common cold) is the most common cause of a stuffy and/or runny nose, but allergies, influenza, and sinus infections also may cause these symptoms.