I have gastritis and take 2 mylanta double strength chewables a day. can i take it long term? or is it harmful?

Consider evaluation by GI- gastroenterology. Check for H pylori a bacteria that is associated with gastritis and needs antibiotics. May also be eosinophilic esophagitis or related to food intolerance-s ( dairy/ gluten)or just foods. Famotidine or omeprazole are meds that are used in reflux but no medication -even Mylanta- should be taken on a long term basis without physician/ provider oversight.