Alka Seltzer is a combination of Sodium Bicarbonate, aspirin, and anhydrous citric acid. It is formed into a tablet and is taken either in a pill form or put into water and dissolved into Carbonated soluted water. Alka Seltzer usually comes in a container or a small box. It can be found at Pharmacy or any Drug Mart. Alka Seltzer does come in different flavors.