Diagnosis

During the first few days of illness, it can be difficult to distinguish the signs and symptoms of bronchitis from those of a common cold. During the physical exam, your doctor will use a stethoscope to listen closely to your lungs as you breathe.

In some cases, your doctor may suggest the following tests:

• Chest X-ray. A chest X-ray can help determine if you have pneumonia or another condition that may explain your cough. This is especially important if you ever were or currently are a smoker.
• Sputum tests. Sputum is the mucus that you cough up from your lungs. It can be tested to see if you have illnesses that could be helped by antibiotics. Sputum can also be tested for signs of allergies.
• Pulmonary function test. During a pulmonary function test, you blow into a device called a spirometer, which measures how much air your lungs can hold and how quickly you can get air out of your lungs. This test checks for signs of asthma or emphysema.