Inflammation of the mucous membrane in the airways (bronchial tubes) of the lungs, resulting from infection or irritation and causing breathing problems and severe coughing

The symptoms of acute bronchitis usually develop quickly over 24-48 hours and may include:

• An irritating, persistent cough that is at first dry but later with increasing production of clear sputum.
• Central chest pain on coughing. 
• Breathlessness, tightness of the chest and wheezing.
• Slight fever.

Blood-streaked sputum is fairly common and does not necessarily, or even usually, mean that something potentially life-threatening is happening. In about 80 per cent of cases it is a sign of bronchitis.