OBJECTIVES: Chest congestion symptoms, commonly experienced as part of the common cold/upper respiratory tract infections (URTI), can be difficult to observe, complex to describe, and can overlap with other symptoms (e.g. cough). To support future efficacy studies for expectorant drugs, an appropriately developed and validated subjective assessment of chest congestion and related-symptoms is therefore necessary.  The current research explored the qualitative experience of chest congestion to develop patient-reported outcome items with strong content validity for use with children and adults. METHODS: Semi-structured, face-to-face, qualitative interviews were conducted with 49 individuals with either a current cold (n=38) or recent cold (n=11). The sample included 39 children/adolescents (aged 6-17 years old) and 10 adults from two locations in the US. The participants were asked open-ended, exploratory questions about their experience of chest congestion. Creative methods and pictograms, including drawing and animal tasks were used to aid discussions. RESULTS: Eight concepts related to the experience of chest-congestion were reported by participants: difficulty breathing, chest tightness, chest heaviness, ‘stuff’ in chest, chest pain, stuffed up or clogged up, difficulty clearing mucus and noise when breathing. Difficulty breathing and difficulty clearing mucus were the most frequently experienced chest symptoms across all age groups. Descriptions for difficulty clearing mucus varied by age, with younger children using words such as ‘goo’ and ‘gunk’ to describe the mucus. Chest pain was reported spontaneously by almost half of the sample but was frequently associated with another symptom (e.g. cough). The more complex concepts of ‘chest heaviness’ and ‘chest tightness’ were experienced by participants of all ages, but were rarely reported spontaneously by the younger children. CONCLUSIONS: There was consistency in the symptoms reported by children and adults but younger children were less likely to spontaneously report the more complex symptoms. Using age-appropriate language, pictograms and creative tasks can help elicit content from younger children.