Green Mucus: When to See a Doctor

Coughing up green mucus indicates a respiratory infection with neutrophilic inflammation (green color from myeloperoxidase).

See a clinician if:

• Fever >101°F (38.3°C) or persistent fever.
• Shortness of breath, chest pain.
• Symptoms >10 days without improvement.
• Worsening after initial improvement ("double sickening").
• Hemoptysis (blood in sputum).
• Underlying lung disease (COPD, asthma, bronchiectasis).

Possible causes: bacterial bronchitis, pneumonia, sinusitis, COPD exacerbation. Treatment may include antibiotics if bacterial.