Hi Dr. Collison,
How can you tell if your child's cough is due to illness or asthma?
Coughs vary greatly and can be caused by many different issues. In trying to determine the cause of the cough, we have to look at many different characteristics in order to figure out the cause and then formulate the appropriate treatment.
Coughs caused by illnesses, such as a cold, allergies, or even pneumonia, tend to sound wet, mucusy and productive. Coughs you would describe as dry and tight are more likely to be caused by asthma. Coughs caused by croup can also be a tight, dry cough but is caused by a viral illness. This cough is usually described as barky or sounding like a seal. It is not always this simple to diagnose but just the sound of the cough can be a good clue as to what might be causing the problem.
If a patient already has a diagnosis of asthma, then the question would be whether the asthma is contributing to the cough or not. Asthma is a chronic condition caused by inflammation in the airways of the lungs. This causes constriction of the airways and leads to wheezing and coughing of varying degrees. Wheezing is a noise heard in the lungs with a stethoscope, although at times can be heard by the unaided ear. It sounds like the whistling noise of air trying to get through a constricted tube. If we hear wheezing during our exam, then we can feel pretty confident that asthma symptoms are contributing to the cough.
If the patient has not been diagnosed previously with asthma, the initial diagnosis would be based on the physical exam, again looking for wheezing along with a dry, tight-sounding cough. Kids can also have wheezing and asthma-like symptoms with an illness. They can wheeze with a cold or pneumonia, whether they have had similar episodes in the past or not. There is also a diagnosis called cough-variant asthmas where the patient will cough like an asthma patient would but they do not have the wheezing on physical exam. This is often diagnosed over time if patients are having repeated episodes of cough without cold symptoms or wheeze.
To summarize, many variables are looked at as we determine the cause for a cough. The wetter or mucusy the cough, the less likely it is to be from asthma. Dry, tight coughs are more likely to be from asthma symptoms, but not in every case. This is a good question that can be best answered by your pediatrician, taking into account the story of the cough and putting the physical exam findings together with it.
Hope this helps!