Coughing up clear phlegm

Mucus from the nose can drain into the throat during allergic rhinitis or a common cold. Acute bronchitis can irritate the airways after a viral illness. Asthma may cause cough, wheeze, or chest tightness, while acid reflux can trigger cough after meals or when lying down. Persistent daily mucus may need assessment for chronic cough or bronchiectasis. In young children, bronchiolitis can affect breathing and feeding.

Drink fluids, rest, and avoid tobacco smoke, vaping, and strong fumes. Warm drinks may soothe the throat. Treat nasal congestion with saline if postnasal drainage seems likely. Notice whether meals, lying down, exercise, cold air, or allergens bring on the cough. Do not use antibiotics left over from another illness; a clinician can decide whether medication is appropriate after assessing the cause.

Get urgent help for severe breathing difficulty, blue or grey lips, chest pain, confusion, coughing blood, or sudden deterioration. A child with fast breathing, pauses, poor feeding, or unusual sleepiness needs prompt assessment. Arrange a review when the cough persists, repeatedly disrupts sleep, causes wheezing, or comes with fever, weight loss, night sweats, or worsening breathlessness.

Ask whether the mucus suggests postnasal drainage, reflux, asthma, or infection; whether inhalers or other treatment are needed; and which changes should lead to urgent review.