SELF Magazine talked to Dr. Alex Li, L.A. Care's Deputy Chief Medical Officer, in "Here’s When to See a Doctor About That Persistent Cough". The article lets consumers know when to be concerned about a persistent cough, and what signs and co-occurring symptoms make it serious enough to see your health care provider.
If you have a history of smoking and can't shake a cough, you should see your doctor to check on the state of your lungs. You should also get help if your cough is causing fatigue by keeping you up at night, or if it’s otherwise affecting your ability to function normally.
--Alex Li, MD
Deputy Chief Medical Officer, L.A. Care
The article reports that doctors consider a cough "chronic" when it lasts for eight weeks or more, and if you've hit that point, you should definitely see your doctor. Other examples of factors that need medical attention are coughing up blood, struggling to breathe or wheezing and having chest pain and fever.