Rantac Mint Syrup is used to treat indigestion, heartburn and acid reflux. Rantac Mint Syrup is also used for gastro-oesophageal reflux disease (GORD) when you get acid reflux. Rantac Mint Syrup is also used to prevent and treat stomach ulcers. Often, Rantac Mint Syrup is taken for a rare condition caused by a pancreatic or intestine tumour called Zollinger-Ellison Syndrome.