Alka-Seltzer is an effervescent antacid and pain reliever first marketed by the Dr. Miles Medicine Company of Elkhart, Indiana, United States. Alka-Seltzer contains three active ingredients: aspirin (acetylsalicylic acid) (ASA), sodium bicarbonate, and anhydrous citric acid. The aspirin is a pain reliever and anti-inflammatory, the sodium bicarbonate is an antacid, and the citric acid reacts with the sodium bicarbonate and water to form effervescence. Alka-Seltzer is a combination of sodium bicarbonate, aspirin, and anhydrouscitric acid, used for the relief of heartburn, acid indigestion, and stomach aches. Alka Seltzer products that help relieve heartburn, acid indigestion, sour stomach and pain.