A child with a bad cough for a month may be due to lung infection, cough variant asthma, tuberculosis and other diseases. 1. Lung infection: if the child is attacked by bacteria, viruses, mycoplasma, etc., resulting in tracheitis, bronchitis, etc., and the inflammatory reaction may lead to lung infection, which may cause the child to develop a chronic cough, resulting in a bad cough for a month. 2. Cough variant asthma: if the child is mainly in the morning and at night when the cough symptoms aggravated, may be suffering from a hundred cough variant asthma, so there will be a month of coughing is not good situation. 3. Tuberculosis: If a child’s cough is not good for a month, accompanied by night sweats (sweating abnormally after going to sleep, waking up after sweating stops), weight loss, wasting and other symptoms, it may be infected with tuberculosis. There may be other reasons why a child’s cough is not good for a month, so it is recommended that parents take their children to see a doctor to clarify the cause of the illness and take corresponding treatment measures.