Is a muscle relaxant also effective for bruxism?

Maybe: I have honestly not prescribed muscle relaxants specifically for bruxism because my patients have bruxism plus spasticity in other areas. But I have used Botox injections and they are very effective.

Not much: We very rarely use this for bruxism because it does not address anything found to be a cause of bruxism. Side effects of drowsiness and feeling lousy the next day overwhelm the usefulness. If the muscles are very acutely sore, relaxants may be used for a night or two, but not longer.

A little: Drugs such as muscle relaxants have a temporary effect on jaw muscle activity, although the maintenance of their therapeutic efficacy, their long term tolerability and risk of addiction need further investigation. Better to treat the source of the bruxism. See a TMJ expert.