Alginic acid makes a protective foam layer that floats on top of the contents of your stomach. Reflux suppressants like Gaviscon contain alginic acid which is made from seaweed. Acid reflux (heartburn) is when stomach acid travels up your food pipe (esophagus) and gives you a burning feeling in your chest. Gaviscon is a type of medicine called a ‘reflux suppressant’ that is indicated for the treatment of heartburn (acid reflux) and indigestion. Serious allergic reaction What is Gaviscon