Symptoms of popcorn lung (bronchiolitis obliterans) include:

• Persistent dry cough, often worsening over time and not improving with usual treatments

• Shortness of breath, especially during or after physical activity or exercise

• Wheezing or noisy breathing without asthma or cold

• Fatigue and unexplained tiredness

• Chest tightness or discomfort

• Occasional low-grade fever and night sweats

• In some cases, coughing up mucus, especially during or after exertion

Symptoms typically develop gradually over weeks to months after exposure to harmful chemicals (like diacetyl found in some flavorings and e-cigarettes), respiratory infections, or other triggers

. They can mimic other lung diseases such as chronic obstructive pulmonary disease (COPD) and may worsen progressively if untreated

. In infants, additional signs may include rapid breathing, blue lips or fingernails, difficulty feeding, and delayed development

. Because popcorn lung causes inflammation and scarring in the smallest airways of the lungs, these symptoms reflect impaired airflow and lung function