Why are they used: Human bodies tend to produce large quantities of acids, mainly consisting of hydrochloric acid. The purpose of this is to assist with digestion of food and to eliminate and foreign bacteria and germs. There is a mucus-like barrier which sits along the stomach lining, preventing the acid from causing any damages. However, in some cases this barrier can be impaired, in which case the stomach has no protection from the acids in the body. Another issue could be that the muscles which are supposed to keep the stomach closed are not doing so effectively enough, giving the stomach acid enough space to flow through in places where is doesn't belong. These sorts of mistakes made by the body, could lead to acid reflux resulting in heartburn, inflammation and digestive pains. Antacids are used to relieve the pains caused by these mishaps.