AB Phylline Syrup is used to prevent and treat symptoms of asthma and chronic obstructive pulmonary disease (COPD). It contains Acebrophylline, which works by relaxing muscles and widening the airways of the lungs. Additionally, it also acts as a mucolytic (cough/sputum thinner) agent and helps in thinning and loosening phlegm (mucus) in the lungs, windpipe and nose. Thereby, it helps to cough out easily and makes breathing easier by opening airways. Some people may experience diarrhoea, nausea, vomiting, dizziness, heartburn, stomach discomfort, skin rash or drowsiness. Before taking this medicine, you should tell your doctor if you are allergic to any of its components or if you are pregnant/breastfeeding, and about all the medications you are taking and pre-existing medical conditions.