Heartburn is a form of indigestion felt as a burning sensation in the chest when stomach acid comes back up into the esophagus. some people take an antacid to relieve heartburn. which best describes the antacid’s effect? the antacid is basic and will neutralize the base entering the esophagus. the antacid is basic and will neutralize the acid entering the esophagus. the antacid is acidic and will raise the ph of the esophagus. the antacid is acidic and will lower the ph of the esophagus.