Acidic sputum may be associated with a combination of gastroesophageal reflux (GERD) and coughing up sputum after eating acidic foods in combination with illnesses that can cause coughing up sputum (e.g., respiratory tract infections).
Coughing up sputum can be caused by a variety of reasons, the most common being respiratory infections. If gastroesophageal reflux (GERD) is combined with phlegm coughing, it can lead to a sensation of acidic sputum as stomach juices can be refluxed through the esophagus into the mouth, where they may partly mix with the phlegm, and the stomach juices themselves can be acidic.
Or, if you have just eaten acidic food, such as sour plums and vinegar, and then cough up phlegm, you may also feel that your phlegm is acidic.
In addition, it may be due to psychological reasons, the specific cause of the disease needs to be clarified after medical examination, and follow the doctor’s instructions for treatment.