Bronchitis is an inflammation of the lining on the large airways of the lung (the large bronchi). The inflammation is usually due to a viral infection, but there may also be a secondary bacterial infection. Bronchitis usually follows an upper respiratory infection (common cold, pharyngitis or influenza). With inflammation of the bronchi, the glands in the walls of the large airways produce excessive secretions (mucus or phlegm) with a ‘productive cough’. These secretions may partially block the airways. Children with bronchitis do not have breathing difficulties (the only lower respiratory tract infection that does not cause breathing difficulties in children). Bronchitis in children is usually acute and recovers in 1 to 2 weeks. Bronchitis is more common in a smoky environment (cigarette smoke or an open fire in the home) and is usually seen in older children.