Whether or not breastfeeding is possible during breastfeeding depends on the specific cause of the cough and phlegm, and the medication used, as follows: 1. 2. No breastfeeding: If the coughing and sputum is caused by infectious diseases, you cannot breastfeed, such as coughing and sputum caused by influenza, coughing and sputum caused by tuberculosis, or coughing and sputum caused by viral pneumonia, you cannot breastfeed normally because it is highly contagious and easily infectious. This is because they are highly contagious and can be easily transmitted.