Postural tremors (tremor when a limb is held outstretched)

Alcohol or another sedating substance (such as a benzodiazepine) when use is stopped

Agitation and a fine tremor starting 24–72 hours after the last use of alcohol or a another substance

Sometimes high blood pressure, a rapid heart rate, or fever, especially in people who are hospitalized

A doctor's examination

Medication or other substances, such as

• Beta-adrenergic medications (used to treat asthma)

• (used to treat bipolar disorder)

• SSRIs (a type of antidepressant)

• (used to treat breast cancer)

• Valproate (an antiseizure medication)

History of medication or substance use

Stopping the medication of substance to see whether the tremor goes away

Hormonal, metabolic, and toxic abnormalities that affect the brain:

• Brain damage due to lack of oxygen (anoxic encephalopathy)

• Liver failure causing brain dysfunction (called hepatic encephalopathy)

• An overactive thyroid gland (hyperthyroidism)

• Kidney failure causing brain dysfunction (called uremic encephalopathy

• Overactive parathyroid glands (hyperparathyroidism)

• Low blood sugar (hypoglycemia)

• Poisons, including heavy metals such as lead

A tremor plus one or more of the following:

• Coma or lethargy (suggesting brain dysfunction)

• Quick, lightning-like muscle contractions (called myoclonus)

• Symptoms of an underlying disorder, such as hyperthyroidism

For hyperthyroidism: Difficulty tolerating heat, excessive sweating, an increased appetite, weight loss, bulging eyes, and frequent bowel movements

Tests to help identify the cause, such as blood tests

• To evaluate how well the liver, thyroid gland, kidneys, and parathyroid glands are functioning

• To measure blood sugar

• To check for poisons

Essential tremor

A persistent tremor that

• Worsens slowly, over many years

• Usually affects both arms and sometimes the head and voice

• Often occurs in people with a family history of tremor

• Usually lessens when people drink small amounts of alcohol or take low doses of sedatives

No other symptoms of nervous system malfunction

A doctor's examination

Physiologic tremor

A fine, rapid tremor that

• Occurs in otherwise healthy people

• May become more noticeable when people take or stop taking certain drugs or feel stressed or anxious

• Usually lessens when people drink small amounts of alcohol or take low doses of sedatives

A doctor's examination

Resting tremor

Parkinsonism triggered by a drug, such as certain antipsychotic medications and medications used to relieve nausea

A history of medication or substance use

Stopping the medication or substance to see whether the tremor goes away

Parkinson disease

A slow alternating tremor that

• Often involves moving the thumb against the index finger as if rolling moving small objects around (called pill rolling)

• Sometimes also affects the chin or a leg

• Usually starts on one side

• Is accompanied by other symptoms, such as muscle stiffness, shaky and tiny handwriting, slow movements, and a shuffling walk

Often no family history of tremor and no lessening of tremor after drinking alcohol

A doctor's examination

Progressive supranuclear palsy

A sometimes coarse or jerky tremor that is often inconspicuous

In older adults who have difficulty looking down and eventually looking up, muscle stiffness, difficulty moving, early falls, and dementia

A doctor's examination

Intention tremor

Cerebellar disorders:

• Chronic alcoholism

• Friedreich ataxia

• Hemorrhage

• Head injury

• Multiple sclerosis

• Spinocerebellar ataxias

• Stroke

• Tumor

A slow tremor that

• Usually occurs on one side of the body

• Is accompanied by lack of coordination (ataxia), especially when attempting to touch or grasp a targeted object or perform rapid alternating movements

• Affects the muscles used in speech, making the voice tremble

In some people, a family history of the disorder (as for Friedreich ataxia or spinocerebellar ataxias)

MRI of the brain

Medications or other substances, such as

• Alcohol

• Beta-adrenergic agonists (used to treat asthma)

A history of use of a medication or other substance

Stopping the medication or substance to see whether the tremor goes away

Complex tremors

Disorders that affect many of the nerves outside the brain and spinal cord (polyneuropathies):

• Guillain-Barré syndrome

• Diabetes

A tremor that

• Varies in speed and width

• Often occurs when people reach for an object and worsens as they get closer to the object

• Often worsens when people hold a limb outstretched

• Is accompanied by other symptoms of nerve damage, such as weakness, a pins-and-needles sensation, and loss of sensation

Electromyography (stimulating muscles and recording their electrical activity)

Other tests to identify the cause

Functional (psychogenic) tremor (due to psychologic factors)

A tremor that

• Begins suddenly or may stop just as suddenly

• Varies in speed and width

• Lessens when people are distracted

A doctor's examination