Dantrolene belongs to a group of medicines called muscle relaxants. Muscle relaxants are medicines that are used to prevent or reduce muscle spasms and spasticity. Muscle spasms occur when there is an uncontrolled (involuntary) contraction of a group of muscles. This often causes pain and discomfort. Spasticity occurs when the muscles contract tightly and then become stiff and harder to use.
This is a companion discussion topic for the original article at https://patient.info/medicine/dantrolene-for-chronic-muscle-spasm-dantrium