alka-seltzer heartburn relief 36 effervescent tablets, lemon lime alka-seltzer alka-seltzer heartburn relief extinguishes the fire of your worst heartburn. its aspirin-free effervescent formula starts to work the instant you take it. 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. and to break up your worst cold symptoms, try alka-seltzer plus cold.