Other causes include the use of drugs (such as amphetamines, caffeine, corticosteroids, SSRI), alcohol
abuse or withdrawal, mercury poisoning
, Phenylketonuria. overactive thyroid or liver failure. Tremors can be an indication of hypoglycemia, along with palpitations, sweating and anxiety. Tremor can also be caused from lack of sleep or vitamins, or Stress (biological)stress.