Green phlegm and COVID: what to know

Green phlegm may result from immune cells, airway inflammation, or mucus that has thickened. COVID can cause cough and phlegm in some people, but the colour is not a reliable way to identify it. Acute Bronchitis, Chronic Sinusitis, Bronchiectasis, COPD, and Pneumonia can also produce green or yellow mucus. A positive or negative test, the timing of symptoms, fever, breathing, and other exposures provide more useful context than colour alone.

Follow current local guidance for testing and reducing close contact when a contagious respiratory infection is possible. Rest, drink fluids, avoid smoke, and use a mask around vulnerable people if appropriate. Keep track of fever, breathing, chest discomfort, hydration, and whether phlegm is becoming blood-stained. Do not start leftover antibiotics: they do not treat viral illness and may be unsuitable. A clinician can assess whether Antibiotic Treatment or another approach is warranted.

Get emergency help for severe or worsening breathlessness, chest pressure, confusion, fainting, blue lips, or difficulty staying awake. Seek prompt medical advice for coughing blood, dehydration, persistent fever, worsening chest pain, or symptoms that are not improving. Ask earlier for help if you are pregnant, immunocompromised, or have a chronic lung condition.

Ask which test is appropriate and when to repeat it if symptoms continue. Ask how to protect household members, whether your current medicines need review, and which breathing changes require emergency care.