Other Information: Each Tablet Contains: Sodium 575 mg. Phenylketonurics: Contains phenylalanine 5.6 mg per tablet. Store at room temperature. Avoid excessive heat. Alka-Seltzer Heartburn in water contains principally the antacid sodium citrate as the principal active ingredient. Misc: Anhydrous Citric Acid/Antacid. Sodium Bicarbonate/Antacid. Fast, Cooling Relief of: heartburn; acid indigestion. Aspirin-free. Alka-Seltzer Heartburn extinguishes the fire of your worst heartburn. Its aspirin-free effervescent formula starts to work the instant you take it. Questions or Comments? 1-800-986-0369 (Mon - Fri 9 am - 5 pm EST). For effective relief of acid indigestion and upset stomach with headache or body aches and pains, try Original Alka-Seltzer, also available in great tasting Lemon-Lime. For extra strength, try Extra Strength Alka-Seltzer Antacid and Pain Relief Medicine and to break up your worst cold symptoms, try Alka-Seltzer Plus Cold. Made in Germany.