The product’s ingredients changed over time, as various artificial sweeteners were banned by the FDA. At certain times it was sweetened with cyclamates and saccharin. At one point the directions instructed children to add sugar and ice. In the early seventies, the manufacturer concluded that it would not be able to make a version that was both legal and sufficiently palatable to be profitable, and so discontinued the product. [when?]

After the introduction of NutraSweet, the brand was resurrected by Premiere Innovations, Inc. in the mid-1990s but its availability was short-lived and the company disappeared. Premiere Innovations marketed Fizzies as “Instant Sparkling Drink Tablets” that were “also great in milk”, “only 10 calories” and “Vitamin C enriched”.

The Fizzies brand reappeared in the 2000s. Previously owned and manufactured by Amerilab Technologies in Plymouth, Minnesota, Fizzies Drink Tablets were available in candy stores and through online retailers.

As of 2012, Fizzies was available in nine flavors: lemonade, root beer, cherry, orange, blue razz, hot cocoa, hot apple cider, cherry cola, and grape. It was marketed as a nostalgic drink to the baby boomer generation and as a fun way for kids to make their own flavorful drinks. In the past incarnation, the product had only 5 calories, was sweetened with sucralose, and contained Vitamin C in the form of ascorbic acid.[3] In February or March of 2016, Fizzies was again discontinued.

https://en.wikipedia.org/wiki/Fizzies

https://www.youtube.com/watch?v=aqCegJd2HRQ&t=1s