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Tremor !tre-mur

by Hector A. Gonzalez-Usigli, MD, Alberto Espay, MD

A tremor is an involuntary, rhythmic, shaking movement of part of the body, such as the hands, head, vocal cords, trunk, or legs. Tremors occur when muscles repeatedly contract and relax.

Types of Tremors

Tremors are usually classified based on when they occur:

  • Resting tremor: Occurring mainly at rest

  • Intention tremor: Triggered by movement toward a target (for example, reaching for a glass)

  • Postural tremor: Triggered by holding a limb outstretched in one position

Tremors can also be classified by what causes them (see Cervical Dystonia : Causes). Examples include the following:

  • Physiologic (the normal tremors that everyone has to some degree)

  • Essential (a common disorder that rarely causes any other symptoms)

  • Cerebellar (caused by damage to part of the brain called the cerebellum)

  • Secondary (caused by a disorder or drug)

Other important characteristics of tremors are

  • How fast the shaking is (frequency): Slow to fast

  • How wide the movement is (amplitude): Fine to coarse

  • How often the tremor occurs: Intermittent to constant

  • How severe it is

  • How rapidly it appears: Sudden to gradual

Resting tremor

This tremor occurs when muscles are at rest. An arm or a leg shakes even when a person is completely relaxed. The tremor becomes less noticeable or disappears when the person moves the affected muscles. Resting tremors are often slow and coarse.

These tremors develop when nerve cells in the part of the brain called the basal ganglia are disturbed. Such disturbances usually result from Parkinson disease. However, they can result from use of drugs that can affect this part of the brain, such as antipsychotic drugs and some drugs used to relieve nausea.

Resting tremors may be socially embarrassing, but because they go away when people try to do something (such as drinking a glass of water), they typically do not interfere with daily activities.

Intention tremor

This tremor occurs during a purposeful movement, as when reaching for an object with the hand. People may miss the object because of the tremor. Intention tremors worsen as people get closer to the targeted object. These tremors are relatively slow and coarse.

Intention tremors may result from damage to the cerebellum, the part of the brain responsible for balance and coordination. Thus, cerebellar tremor and intention tremor may be used as synonyms.

Certain hereditary disorders that affect the cerebellum (called spinocerebellar ataxias) are a common cause of intention tremors, as is multiple sclerosis. Stroke, a tumor, alcoholism, and overuse of sedatives or anticonvulsants can also cause the cerebellum to malfunction, resulting in an intention tremor.

Did You Know...

  • Everyone has tremors to some degree.

  • If the tremor is mild, some simple measures, such as holding objects close the body, can make functioning easier.

Postural tremor

This type of tremor is most obvious when a limb is held in a position that requires resisting the pull of gravity, as when people hold their arms outstretched. The most common postural tremors are essential tremor and physiologic (normal) tremor.

Complex tremor

Complex tremor is a tremor that has features of more than one type of tremor. Common causes of complex tremors are psychologic factors and widespread nerve damage such as that caused by diabetes or Guillain-Barré syndrome.


Tremors can be normal (physiologic) or abnormal. Many disorders can cause tremor (see Table: Some Causes and Features of Tremor).

Most commonly, tremors are

  • Physiologic tremor (most common overall)

  • Essential tremor

  • Due to Parkinson disease

  • Due to a stroke or multiple sclerosis affecting parts of the brain that control movement

  • Due to hereditary disorders involving the cerebellum, such as Friedreich ataxia (see Friedreich ataxia) and spinocerebellar ataxias (see Spinocerebellar ataxias (SCAs))

  • Psychogenic tremor (due to psychologic factors)

Physiologic tremor is the normal tremor that everyone has to some degree. For example, most people's hands, when held outstretched, usually tremble slightly. Such slight, rapid tremor reflects the precise moment-by-moment control of muscles by nerves. In most people, the tremor is barely noticeable. However, a normal tremor may become more noticeable under certain conditions and may worry people. For example, the tremor may be more noticeable when people

  • Feel stressed, anxious, tired ,or sleepy

  • Stop drinking alcohol or taking a sedative (such as a benzodiazepine) or an opioid

  • Consume caffeine

  • Take certain drugs, including theophylline and albuterol (which are used to treat asthma and COPD), corticosteroids, and recreational drugs (such as cocaine or amphetamines)

Essential tremor results from a problem in the nervous system, but people with this tremor rarely have any other symptoms of nervous system dysfunction (neurologic symptoms). The cause is unclear, but the tremor often runs in families.

Essential tremor usually begins during early adulthood but can begin at any age. The tremor slowly becomes more noticeable as people age. Thus, it is sometimes incorrectly called senile tremor. The tremor usually involves the arms and hands and sometimes affects the head. When it affects the head, people may look as if they are nodding yes or shaking their head no. These tremors are usually worsened by holding a limb outstretched (against gravity) or by moving a limb.

Usually, essential tremor remains mild. However, it can be troublesome and embarrassing. It can affect handwriting and make using utensils difficult. In some people, the tremor gradually worsens over time, eventually resulting in disability. Symptoms may resemble those of Parkinson disease, and sometimes essential tremor is misdiagnosed as Parkinson disease.


The following information can help people decide when a doctor's evaluation is needed and help them know what to expect during the evaluation.

Warning signs

The following symptoms are cause for concern:

  • Tremors that start abruptly

  • Other neurologic symptoms, such as a change in mental status, muscle weakness, changes in the way a person walks, and difficulty speaking

  • A rapid heart rate and agitation

When to see a doctor

People with warning signs should see a doctor immediately. People without warning signs should see a doctor as soon as possible, but a delay of a week or two (or slightly longer if the tremor has developed over months or years) is usually not harmful.

If people are under 50 years old and do not have a family history of tremor, being evaluated by a doctor is important to make sure that the cause is not another disorder or a drug.

What a doctor does

Doctors first ask questions about the person's symptoms and medical history and then do a physical examination. What doctors find during the history and physical examination often suggests a cause and the tests that may need to be done (see Table below).

Doctors ask whether the tremor began gradually or suddenly, which body parts are affected, what triggers it (such as movement, rest, or standing), and what relieves or worsens it (such as alcohol, caffeine, stress, or anxiety). If the tremor began suddenly, doctors ask about events that may have triggered it (such as a recent injury or use of a new drug).

Doctors review the person's past medical history, looking for conditions associated with tremor (see Table: Some Causes and Features of Tremor). They ask about tremors in close relatives. They review the drugs taken and ask about use of caffeine, alcohol, and recreational drugs (particularly whether the person recently stopped using such drugs).

Doctors do a physical examination, paying particular attention to the neurologic examination (including the way the person walks—see Physical Examination). Doctors note which body parts are affected by the tremor. They observe how fast the shaking movements are in various situations:

  • When the affected body parts are at rest and when they are fully supported (for example, hands in the person's lap)

  • While the person maintains certain positions (such as holding the arms outstretched)

  • While the person is walking or doing tasks with the affected body part

The quality of the person's voice may be observed when holding a long note.

Some Causes and Features of Tremor




Postural tremor (tremor when a limb is held outstretched)

Alcohol or a sedative (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 benzodiazepine

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

A doctor's examination

Drugs, such as

  • Amitriptyline

  • Beta-agonists (used to treat asthma)

  • Cocaine

  • Haloperidol

  • Lithium

  • SSRIs

  • Tamoxifen

  • Valproate

History of drug use

Stopping the drug 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 (hepatic encephalopathy)

  • An overactive thyroid gland (hyperthyroidism)

  • Kidney failure

  • Overactive parathyroid glands (hyperparathyroidism)

  • Low blood sugar (hypoglycemia)

  • Poisons, including heavy metals such as lead

A tremor plus coma or lethargy and symptoms of an underlying disorder such as

  • 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 identify poisons

Essential tremor

A coarse or fine, slow 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

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 (see Causes above) or feel stressed, anxious, tired, or sleepy

  • 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 drugs and drugs used to relieve nausea

A history of drug use

Stopping the drug 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 Parkinson disease or tremor and no lessening of tremor after drinking alcohol

A doctor's examination

Use of the drug levodopa to see whether improvement occurs

Intention tremor

Cerebellar disorders:

  • Chronic alcoholism

  • Friedreich ataxia

  • Hemorrhage

  • 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, 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

Drugs, such as

  • Alcohol

  • Anticonvulsants (such as phenytoin and valproate)

  • Beta-agonists

  • Cyclosporine

  • Lithium

  • Tacrolimus

A history of drug use

Stopping the drug 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)

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

*Features include symptoms and results of the doctor's examination. Features mentioned are typical but not always present.

MRI = magnetic resonance imaging; SSRIs = selective serotonin reuptake inhibitors (a type of antidepressant).


Doctors can usually identify the type of tremor based on its characteristics and results of the medical history and physical examination. For example, if the tremor develops gradually, it is usually physiologic or essential tremor. If a postural tremor starts more suddenly, the cause may be psychologic factors, a poison, a disorder (such as hyperthyroidism), stopping use of alcohol or another drug (such as a sedative), or use of a drug known to cause tremor.

Brain imaging with magnetic resonance imaging (MRI) or computed tomography (CT) is done if

  • The person has other neurologic symptoms.

  • The tremor started suddenly or progresses rapidly.

For people with postural tremors, testing may also include blood tests to check for possible causes. Tests may include measurement of blood sugar and tests to evaluate how well the thyroid and parathyroid glands, liver, and kidneys are functioning.


Any specific cause is treated when possible—for example, by stopping a drug that is causing the tremor or by treating hyperthyroidism. Parkinson disease can be treated with levodopa and other drugs.

For mild tremor, no treatment is needed. If tremors become bothersome, some simple measures can help:

  • Grasping objects firmly and holding them close to the body to avoid dropping them

  • Avoiding uncomfortable positions

  • Not eating soup in public

  • Using assistive devices, as instructed by an occupational therapist

Assistive devices may include rocker knives, utensils with large handles, and, particularly if the tremor is severe, button hooks, Velcro fasteners (instead of buttons or shoe laces), zipper pulls, straws, and shoe horns.

For physiologic or essential tremor, eliminating or minimizing the trigger may lessen the tremor. For example, avoiding caffeine, getting enough sleep, and minimizing stress may help. For some people, drinking alcohol in moderation may lessen the tremor, but doctors do not recommend this tactic as a treatment. Heavy drinking followed by suddenly stopping makes the tremor worse. If many daily activities (such as using utensils and drinking from a glass at mealtime) become difficult or if the person's work requires steady hands, drug therapy may help. It may include a beta-blocker (such as propranolol), the anticonvulsant primidone, or both. For physiologic tremor, occasionally taking a low dose of a benzodiazepine (a sedative), such as lorazepam, may help lessen the tremor.

Intention tremors are difficult to treat, but if the condition causing it can be corrected, the tremor may resolve. If the condition cannot be corrected, a therapist may put wrist and ankle weights on the affected limb to reduce the tremor. Or people may be taught to brace the limb during activity. These measures sometimes help.

Deep brain stimulation

Tiny electrodes are placed in the area of the brain involved in tremors. The electrodes deliver a painless shock to block the impulses causing tremors. Deep brain stimulation is sometimes done when drugs cannot control a severe, disabling tremor. Sometimes essential tremors or tremors due to Parkinson disease or another disorder require such treatment. Such treatments are available only at special centers.

Essentials for Older People

Many older people think that developing a tremor is a part of normal aging and may not seek medical attention. Nonetheless, older people should talk to their doctor, who can ask them questions and do a physical examination to check for possible causes of tremor. Doctors may then recommend strategies or possibly drugs to lessen the tremor.

Also, older people are more likely to be taking drugs that cause tremor and are more vulnerable to side effects of these drugs. Thus, when prescribing such drugs to older people, doctors try to prescribe the lowest effective dose. Such a dose may be lower than the doses used to treat younger adults.

Tremor can significantly affect quality of life in older people, interfering with their ability to function, especially if they have other physical or mental impairments. Physical and occupational therapists can provide simple coping strategies, and assistive devices may help older people maintain quality of life.

Key Points

  • Tremors can be classified based on when they occur: when at rest (resting tremor), when moving toward a target (intention tremor), or when holding a limb outstretched (postural tremor).

  • Most tremors are physiologic (normal) tremors, and some are essential tremor or are caused by other disorders.

  • Tremors that occur during rest are often caused by Parkinson disease.

  • Doctors can usually identify the cause based on the history and physical examination.

  • If a tremor begins suddenly or is accompanied by other neurologic symptoms, people should see a doctor right away.

  • People who are under 50 and have tremor should see a doctor.

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