Effervescent or carbon tablets are tablets which are designed to dissolve in water and release carbon dioxide. The carbon dioxide is generated by a reaction of a compound containing bicarbonate, such as sodium bicarbonate or magnesium bicarbonate, with an acid such as citric acid or tartaric acid. Both compounds are present in the tablet in powder form and start reacting as soon as they dissolve in water.[1][2][3][4]
Effervescent tablets are made by compression of ingredients in the form of powders into a dense mass, which is packaged in blister pack, or with a hermetically sealed package with incorporated desiccant in the cap. To use them, they are dropped into water to make a solution. The powdered ingredients are also packaged and sold as effervescent powders or may be granulated and sold as effervescent granules. Generally powdered ingredients are first granularized before being made into tablets.[5][6]
Effervescent medicinal beverages date back to the late 1800s and originally arose to mask the taste of bitter waters taken as curatives, during the water cure craze of that era.[7]