Dr.Perri Klass, a pediatrician, wrote an interesting article about coughs in the New York Times on 12-22-16. She quoted several so-called experts, but did not emphasis some things I believe parents need to know. If a child has a cold and continues to cough for several days, I would want the child to be seen by a family doctor or pediatrician. If there has not been a fever and the child is eating well and nothing is seen or heard on physical examination, then perhaps a chest X-ray can be put off for a day or so. However, if the cough continues, I would want a chest X-ray to include the neck. I saw a child who had been seen by several doctors for a cough that was thought to be croup. A chest X-ray had been taken and was negative. When I saw the child, I asked that the X-ray be repeated to include the neck and there was a safety pin in the windpipe or trachea. Once it was removed, the cough went away. Lobar pneumonia can show very few symptoms and often can only be seen on a chest X-ray. Sometimes, it takes a few days for the pneumonia to be seen, so a repeat X-ray needs to be done if the cough does not clear up.
When there is a family history of allergy, it may be particularly necessary for a child to be seen by a pediatric allergist. Often household pets, dust or other things can trigger a cough. Croup has a very distinct sound and can be dangerous if it is not adequately treated. When we lived in Rochester, New York, my children both frequently had croup during the winter and we became adept at setting up a croup tent with a cool mist vaporizer running inside of it. Cough medicines that don't suppress the cough can be helpful in older children. A cough medicine that contains DM should not be given to children because coughing helps bring up mucus.