The initial evaluation for a cough lasting longer than 4 weeks should include a chest x-ray. Occasionally, a pulmonary function test looking for evidence of asthma may also be ordered. If your symptoms point toward a certain source (for example, post nasal drip and frequent throat clearing), then this will be treated first to see if the cough goes away.

Unfortunately, there are few specific tests to evaluate cough. Therefore, the diagnostic and therapeutic approach involves trying out different treatments to see which works best. In about 2/3 of patients, there are at least two problems (for example, post nasal drip and mild asthma) contributing to cough. As a result, the cough may improve somewhat with treatment addressing one problem, but may need additional treatment for the other problem(s).

The only way to eliminate a cough is to treat the cause - that is why cough syrups and cough drops don't work. While cough is an annoying and frustrating symptom, it rarely represents a serious medical problem (with a normal chest x-ray). In most cases, the cough is treatable once the underlying problem is understood and treated. If a cough is diagnosed as due to GERD, and the treatment does not relieve the GERD, this does not mean the diagnosis was incorrect - it means a different therapy needs to be tried to treat the GERD. Patience on the part of both patient and physician is sometimes required to successfully figure out the causes of a longstanding cough.