Tremors are a type of involuntary shaking movement. Involuntary means you shake without trying to do so.

See also:

• Drug-induced tremor
• Essential tremor
• Familial tremor
• Hand tremor

Tremors are caused by problems with the nerves supplying certain muscles. They may affect the whole body or just certain areas, as with hand tremor.

Types of tremors include:

• Drug-induced tremor (tremors caused by certain drugs)
• Essential tremor (no known cause)
• Familial tremor (runs in families)

Other causes of tremors may include:

• Alcohol withdrawal
• Cigarette smoking
• Hyperthyroidism
• Parkinson's disease
• Pheochromocytoma
• Too much caffeine
• Use of certain medications
• Wilson's disease

All people have some tremor when they move their hands. Stress, fatigue, anger, fear, caffeine, and cigarettes may temporarily worsen this type of tremor.

Jankovic J. Movement disorders. In: Goetz CG, ed. Textbook of Clinical Neurology. 3rd ed. Philadelphia, PA: WB Saunders; 2007:chap. 34.