Tremor is an unintentional, rhythmic muscle movement involving to-and-fro movements (oscillations) of one or more parts of the body. It’s the most common of all involuntary movements and can affect the hands, arms, head, face, voice, trunk and legs. Most tremors happen in the hands. In some people, tremor is a symptom of a neurological disorder or appears as a side effect of particular drugs. However, the most common of tremor happens in otherwise largely healthy people. Although tremor is not life-threatening, it can be embarrassing to some people and make it harder to perform daily tasks.