Alka Seltzer Original Heartburn Relief and Pain Relief Antacid Tablets bring fast relief of heartburn upset stomach and acid indigestion. Providing trusted and effective relief for more than 80 years Alka Seltzer Original tablets contain anhydrous citric acid and sodium bicarbonate that neutralize acid fast on contact relieving acid indigestion. These Alka Seltzer tablets dissolve in water quickly delivering fast relief that you can hear see and feel working.