Used for: Involuntary, rhythmic, muscle contraction and relaxation involving to and fro movements (oscillations or twitching) of one or more body parts. Involuntary movements may affect the hands, arms. Eyes. Face, head, vocal folds, trunk, and legs. Most tremors occur in the hands. In some people, tremor is a symptom of another neurological disorder. A very common kind of tremor is the chattering of teeth, usually induced by cold temperatures or by fear.