How to diagnose Cough ?
Your doctor will diagnose the cause of your cough based on your medical history, a physical exam, and test results.
                
Medical History
                
Your doctor will likely ask questions about your cough. He or she may ask how long you've had it, whether you're coughing anything up (such as mucus, a slimy substance), and how much you cough.
                
Your doctor also may ask:
                
About your medical history, including whether you have allergies, asthma, or other medical conditions.
                
Whether you have heartburn or a sour taste in your mouth. These may be signs of gastroesophageal reflux disease (GERD).
                
Whether you've recently had a cold or the flu.
                
Whether you smoke or spend time around others who smoke.
                
Whether you've been around air pollution, a lot of dust, or fumes.
                
Physical Exam
                
To check for signs of problems related to cough, your doctor will use a stethoscope to listen to your lungs. He or she will listen for wheezing (a whistling or squeaky sound when you breathe) or other abnormal sounds.
                
Diagnostic Tests
                
Your doctor may recommend tests based on the results of your medical history and physical exam. For example, if you have symptoms of GERD, your doctor may recommend a pH probe. This test measures the acid level of the fluid in your throat.
                
Other tests may include:
                
An exam of the mucus from your nose or throat. This test can show whether you have a bacterial infection.
                
A chest x ray. A chest x ray takes a picture of your heart and lungs. This test can help diagnose conditions such as pneumonia and lung cancer.
                
Lung function tests. These tests measure how much air you can breathe in and out, how fast you can breathe air out, and how well your lungs deliver oxygen to your blood. Lung function tests can help diagnose asthma and other conditions.
                
An x ray of the sinuses. This test can help diagnose a sinus infection.