An over-the-counter (OTC) antacid is often used to relieve mild cases of heartburn or acid reflux. Though they are available without a doctor’s prescription, they should be taken only under a doctor’s advice.As per the American Academy of Family Physicians -

• Different types of antacids have different mechanisms of action.
• To manage an ulcer, an antacid may need to be taken along with an antibiotic.
• If one needs more calcium to help strengthen bones, an antacid that contains calcium carbonate is preferred.
• Antacids may cause minor side effects in some, such as nausea, headache, diarrhea or constipation.
• One must read the label carefully to ensure that he/she is not allergic to any of the ingredients.
• It may not be feasible for those with kidney disease to take all types of antacids.
• An antacid may interact with other medications.

Talk to the doctor before taking an antacid.