Although coughing is often a sign of an upper respiratory infection, a cough that is long lasting can point to other possible causes. A chronic cough is defined as lasting longer than 8 weeks. Some common causes are asthma
, allergies, postnasal drip, certain medications, and acid reflux.
Asthma is a disease of the airways that is normally characterized by difficulty breathing and wheezing. However, some people with asthma have cough as their only symptom (cough-variant asthma) which can be triggered by cold air or pollutants (such as exposure to dust in your boyfriend's case).
Sinus problems and allergies can lead to postnasal drip which can cause a chronic cough. Postnasal drip causes irritation at the back of the throat and patients often complain of a constant "tickle" in their throat that causes them to cough or clear their throat.
GERD, gastroesophageal reflux disease, is when stomach acid flows backwards into the tube that connects your stomach and throat. This causes constant irritation in the back of the throat which can lead to a chronic cough.
These are just a few causes of chronic cough but there are many more, some of which are more serious. Therefore, it is important for your boyfriend to see his primary care doctor
to determine the underlying cause of his cough and obtain appropriate treatment.