Respected Sir, hi I evaluated your query. Reason for chesty cough after drinking alcohol is breaking down of the immune system in the lungs making you more vulnerable to infection and the damage it causes. Many times alcoholics are at increased risk of developing pneumonia and life-threatening acute respiratory distress syndrome (ARDS) for which there is no treatment. But even after knowing all the facts one has his own path to decide whether to live the way they want or to live as per Doctors advises by Quiting these silent killers of the body. Hope I was clear in making satisfactory response to your query. Thanks for using Health Care Magic and reviewing my answer. Regards Bye Enjoy.