Refreshing temporary relief for stomach upsets. Eno is an antacid powder which is mixed with water to produce a sparkling antacid drink for the temporary relief of heartburn & indigestion caused by too much food and drink. Eno works by neutralising the excess acid in the stomach.Formulated with Sodium Bicarbonate, Sodium Carbonate, Citric Acid Anhydrous which helps provide temporary relief from stomach upset.