Antacids control only the symptoms and not the cause. They work by neutralising the acid produced in the stomach… They do not control the cause of production of more acid. Antihistamines are the drugs that suppress the action of histamine which is the chemical responsible for the stimulation of secretion of pepsin and HCl in the stomach.
They influence and prevent the binding of histamine with the receptors present in the stomach walls resulting in lower acid production and therefore, provides better treatment.