TUMS is a commonly used antacid in the USA. Antacids are weak bases that are neutrilize the acidity of gastric HCL. Also reduce pepsin secretion. It is taken orally. It is used for the treatment of heartburn, peptic ulcer and GERD. Upset stomach and indigestion as well. Antacids are taken after food as food in the stomach delays emptying. Aluminum hydroxide and Magnesium Hydroxide are commonly used antacids.