The present disclosure concerns effervescent compositions and methods of making and using the same. In some embodiments, the disclosed effervescent compositions are formed from an input blend comprising an acid and a base by granulating the input blend in a twin-screw processor. The granules formed from the input blend can be formed by an in situ granulating agent, which can be a portion of the acid that melts during granulation. In some embodiments, the effervescent compositions can be made using a twin-screw processor comprising an intake zone for receiving an input blend comprising an acid and a base; a granulation initiation zone for melting only a portion of the acid to serve as an in situ granulating agent; a granulation completion zone for granulating the input blend; and an outlet for discharging the granules.