What Is a Tremor? Understanding Why We Shake and What the Pattern Can Tell Us
Stages of Life Medical Institute
Quick Look A tremor is an involuntary, rhythmic shaking movement—but tremor is a symptom, not a diagnosis. Some tremors are normal and become noticeable with stress, fatigue, caffeine, or medications. Others occur with essential tremor, Parkinson’s disease, metabolic problems, or neurologic disorders. One of the most useful diagnostic clues is surprisingly simple: What are you doing when the shaking occurs? |
“My hands are shaking. Do I have Parkinson’s disease?”
It is a question physicians hear frequently.
The answer is: Not necessarily.
Tremor is one of the most recognizable neurologic symptoms, but it is also one of the most misunderstood. People commonly use the word tremor to describe almost any abnormal shaking or movement. Neurologically, however, tremor has a more specific meaning. A tremor is an involuntary, rhythmic, oscillatory movement of a body part.¹
That definition includes the word "Rhythmic."
Tremor tends to move back and forth in a relatively repetitive pattern. Other abnormal movements—muscle twitching, jerking, spasms, tics, myoclonus, chorea, or dystonia—may look like “shaking” to a patient but are not necessarily tremors. Most importantly: Tremor describes a movement. It does not tell us what is causing it.
That distinction is the key to understanding tremor.
Everyone Has a Little Tremor
Virtually everyone has some degree of tremor. It is called physiologic tremor. Normally, the movement is so small that we do not notice it. Hold your hands straight out in front of you, however, and under the right circumstances you may see a very fine movement of the fingers.
That normal tremor can become more visible with:
anxiety or emotional stress
fatigue
sleep deprivation
caffeine
nicotine
strenuous exercise
certain medications
low blood sugar
excessive thyroid hormone
stimulant drugs
When normal physiologic tremor becomes more noticeable, physicians often call it enhanced physiologic tremor. This is an important starting point because not every visible tremor represents a degenerative neurologic disease. Sometimes the nervous system is functioning normally, but its normal physiologic oscillations have simply become easier to see.
The First Question: When Does the Tremor Occur?
When evaluating tremor, one of the most useful questions is not: “How badly are you shaking?” It is: “What are you doing when you start shaking?”
Neurologists call this the tremor’s activation condition. The International Parkinson and Movement Disorder Society incorporates activation condition, body distribution, history, and associated neurologic findings into the classification of tremor.¹
This gives us several important categories:
Rest Tremor
A rest tremor occurs when the affected body part is relaxed and not voluntarily being used. For example, a person’s hand may shake while resting in the lap but improve when the person reaches for a cup.
Rest tremor is classically associated with Parkinson’s disease, although a rest tremor by itself does not establish that diagnosis.
Postural Tremor
A postural tremor appears when a person holds a body part against gravity. Ask someone to stretch both arms forward and keep them there. A tremor that appears or becomes more obvious in that position is postural.
Enhanced physiologic tremor and essential tremor commonly have postural components.
Kinetic Tremor
A kinetic tremor occurs during voluntary movement. A patient may notice shaking while:
drinking from a glass
using utensils
writing
applying makeup
shaving
buttoning clothing
using a screwdriver
reaching for an object
Essential tremor commonly produces an action or kinetic tremor.
Intention Tremor
An intention tremor becomes progressively more pronounced as the hand approaches a target. During a finger-to-nose examination, for example, the hand may become increasingly tremulous or inaccurate as the finger approaches the nose.
This pattern can suggest dysfunction involving the cerebellum or its connections.
Task-Specific and Position-Specific Tremor
Some tremors appear predominantly during one particular activity. Writing tremor is a classic example. A musician may develop tremor predominantly while playing an instrument. Other patients notice tremor only when the arm, hand, head, or another body part is placed in a particular position.
These patterns can overlap with dystonia and other movement disorders.
Isometric Tremor: Shaking Against Resistance
There is another important type of action tremor that patients may notice primarily when they push, squeeze, grip, or contract a muscle forcefully against resistance.
This is called an isometric tremor.
An isometric tremor occurs during voluntary muscle contraction against a rigid stationary object without purposeful movement of the affected body part.¹
Examples might include shaking while:
pushing firmly against a wall
squeezing an object tightly
pressing one hand forcefully against the other
maintaining force against a stationary object
holding a heavy object in a fixed position
This can be clinically useful because a patient may have little or no visible tremor while the limb is resting or moving freely, yet develop a very reproducible tremor when the involved muscles are placed under sustained contraction. As with other tremors, isometric tremor describes when the tremor appears. It does not tell us why it is occurring.
A tremor occurring only during a particular movement, position, or activity may have overlapping features of a task-specific, position-specific, or dystonic tremor.
Rarely, focal tremor has also been reported in association with peripheral nerve injury or entrapment. This becomes more relevant when localized shaking occurs together with pain, numbness, tingling, weakness, or other findings corresponding to a particular peripheral nerve.
It should not be assumed, however, that shaking produced by pressure or resistance automatically means a nerve is being mechanically compressed.
Where Does the Tremor Occur?
The hands are the most obvious location, but tremor can affect many parts of the body. It may involve the:
hands and arms
head
voice
jaw or chin
trunk
legs
Location provides another diagnostic clue. Head and voice tremor can occur with essential tremor, whereas isolated head tremor may raise consideration of dystonia. Likewise, a tremor beginning predominantly on one side of the body has different implications from a symmetric tremor involving both hands.
This is why simply saying, “I have a tremor,” tells us relatively little. We want to know: Where is it? When does it happen? What activates it? What stops it? The pattern matters.
Essential Tremor: Common, but Not Always “Benign”
Essential tremor is one of the most common movement disorders.
It characteristically produces an action tremor, particularly involving the upper extremities. Current consensus criteria define essential tremor as an isolated syndrome of bilateral upper-limb action tremor lasting at least three years, with or without tremor elsewhere and without certain additional neurologic signs.¹,²
Patients often first notice it during activities requiring precision.
Handwriting becomes shaky.
A spoon begins to rattle. Liquid spills from a cup.
Holding a camera or smartphone steady becomes difficult.
There may be a family history, although not always.
Essential tremor has historically been called “benign essential tremor.” That description can be misleading.
Essential tremor does not usually carry the same implications as Parkinson’s disease, but it can substantially interfere with eating, writing, work, hobbies, and social confidence. A disorder does not have to shorten life to meaningfully affect it.
Does Tremor Mean Parkinson’s Disease?
No.
This may be the most important reassurance in this article. Parkinson’s disease is strongly associated with tremor, but tremor is neither unique to Parkinson’s disease nor required for its diagnosis. The Parkinson’s Foundation estimates that approximately 70% to 90% of people with Parkinson’s disease experience tremor at some point during the course of their illness.³
Turn that statistic around, however, and it makes an equally important point: Some people with Parkinson’s disease never develop a prominent tremor.
You can have a tremor without having Parkinson’s disease—and you can have Parkinson’s disease without having a tremor.
What Does a Parkinsonian Tremor Look Like?
The classic Parkinsonian tremor is a rest tremor. It is most noticeable when the affected hand or limb is relaxed rather than actively performing a task.
A familiar example is the so-called “pill-rolling” tremor, in which repetitive movement of the thumb and fingers can resemble rolling a small object between them.
Parkinsonian tremor commonly:
begins on one side
is most prominent at rest
may decrease during purposeful movement
may reappear after the arms have been held out for several seconds
becomes more noticeable with stress, fatigue, or strong emotion
But Parkinson’s disease is much more than a tremor disorder.
Parkinson’s Disease Is Not Diagnosed From Tremor Alone
Current Movement Disorder Society criteria define parkinsonism as bradykinesia plus either rest tremor or rigidity.⁴
Bradykinesia means more than simply moving slowly. It involves slowness together with progressive reduction in the speed or amplitude of repetitive movements.
Physicians may also find:
muscular rigidity
reduced arm swing
smaller handwriting
decreased facial expression
softer speech
changes in gait
difficulty initiating movement or turning
other motor and non-motor features
Some patients with Parkinson’s disease have relatively little tremor. Their predominant problems may instead be slowness, stiffness, gait dysfunction, or other symptoms. Conversely, someone can have a very noticeable tremor and not have Parkinson’s disease at all.
Essential tremor, enhanced physiologic tremor, medications, caffeine, thyroid abnormalities, metabolic disturbances, dystonia, and other conditions can all produce shaking.
A Useful Rule of Thumb
A tremor that is most apparent at rest and begins asymmetrically raises the possibility of Parkinson’s disease.
A tremor that is most apparent while holding something or performing an activity may be more suggestive of essential tremor or another action tremor.
These are useful clinical clues. They are not absolute rules. Real patients do not always follow textbook patterns, and some people demonstrate more than one type of tremor.
Clinical Pearl
The pattern of a tremor is usually more informative than its severity. A dramatic tremor is not automatically more dangerous than a subtle one.
When evaluating tremor, I want to know:
Is it present at rest?
Does it appear when the arms are extended?
Does it worsen during movement?
Does it appear only when pushing or contracting against resistance?
Does it occur only during one particular task or position?
Did it begin on one side or both?
Which body parts are involved?
How quickly did it develop?
What medications is the patient taking?
What other neurologic findings accompany it?
Those details often tell us far more than how much the hand happens to shake during a single office visit.
Reproducibility matters. If a tremor consistently appears only when a particular muscle group is contracted against resistance—and disappears when that contraction stops—that activation pattern can provide an important diagnostic clue.
Medications Can Cause Tremor
Medication review is an important—and sometimes overlooked—part of evaluating tremor.
A variety of medications can produce or worsen shaking, including some:
stimulants
bronchodilators
antidepressants
mood-stabilizing medications
thyroid medications
immunosuppressants
antiseizure medications
drugs that increase adrenergic activity
Even caffeine and nicotine can amplify tremor.
The lesson is not to stop a prescribed medication because you notice shaking. Instead, ask: Could one of my medications be contributing to this?
Sometimes changing the dose, timing, or medication—when medically appropriate—can substantially improve the problem.
Metabolic and Medical Conditions Matter Too
Not every tremor originates from a primary neurologic disease. A medical evaluation may need to consider:
hyperthyroidism
hypoglycemia
electrolyte abnormalities
liver disease
kidney disease
medication toxicity
alcohol withdrawal
nutritional abnormalities
other metabolic disturbances
This is one reason a good tremor evaluation begins with the whole patient, not simply the shaking hand.
Other Neurologic Causes of Tremor
Tremor can occur with several neurologic conditions, including:
dystonia
cerebellar disorders
multiple sclerosis
stroke
traumatic brain injury
peripheral neuropathy
structural brain disease
certain inherited neurologic disorders
Rarely, focal tremor has been described in association with peripheral nerve lesions or entrapment.
That possibility deserves particular consideration when a very localized tremor occurs with pain, numbness, tingling, weakness, altered reflexes, or symptoms following the distribution of a particular nerve.
There are also tremors whose clinical features do not initially fit neatly into a single category.
The International Parkinson and Movement Disorder Society therefore recommends first characterizing a tremor according to its clinical features and then considering its underlying cause.¹
Sometimes we can accurately describe the tremor before we know exactly why it is occurring.
How I Evaluate a Patient With Tremor
A careful history and physical examination remain extraordinarily valuable.
When did it begin?
A tremor that has slowly progressed over 15 years raises very different considerations from one that appeared yesterday.
Did it begin on one side or both?
Symmetry matters.
What is the activation condition?
Does it occur at rest, while holding the arms forward, during movement, as the hand approaches a target, during a particular task, in one particular position, or while contracting against resistance? That sequence can reveal a remarkable amount of information.
What makes it worse?
Stress? Caffeine? Fatigue? Hunger? Exercise? Medication? Muscular effort?
What makes it stop?
This question can be just as useful. If shaking disappears immediately when resistance is released, for example, that may help characterize an isometric component.
Is there a family history?
Essential tremor frequently occurs in families, although family history is not required.
What medications and supplements are being taken?
This includes prescription medications, over-the-counter drugs, stimulants, supplements, energy products, nicotine, and caffeine.
Then comes the examination. I may observe the hands while they are:
resting in the lap
held forward
maintained in different positions
performing purposeful movements
writing
drawing
reaching for a target
gripping an object
contracting against resistance
An Archimedes spiral—a simple expanding spiral drawn on paper—can be particularly useful for demonstrating an action tremor and documenting its appearance over time.
The examination also looks for rigidity, bradykinesia, gait abnormalities, cerebellar dysfunction, dystonia, weakness, sensory abnormalities, reflex changes, and other neurologic findings.
Laboratory testing or imaging is not necessary for every tremor. When the history suggests a metabolic, medication-related, peripheral nerve, structural, or atypical cause, additional testing may be appropriate.
When Should a Tremor Be Evaluated Promptly?
Most chronic tremor syndromes develop gradually. A sudden new tremor, particularly when accompanied by other neurologic symptoms, deserves more urgent attention.
Seek prompt medical evaluation when shaking occurs with:
new weakness
facial drooping
difficulty speaking
severe imbalance
new confusion
severe headache
loss of consciousness
significant new coordination problems
Likewise, a progressively worsening tremor that interferes with eating, drinking, writing, walking, work, or other daily activities deserves evaluation even when it is not an emergency.
Can Tremor Be Treated?
Often, yes. But treatment depends upon the cause.
If caffeine, medication, thyroid excess, hypoglycemia, or another metabolic problem is amplifying physiologic tremor, addressing the underlying trigger may be the most effective treatment.
Essential tremor has specific medical and procedural treatments. Parkinsonian tremor is approached differently. Dystonic tremor may require another strategy. And a focal tremor associated with a peripheral nerve disorder may require evaluation and treatment of the underlying nerve problem. This is why simply treating “tremor” without first determining what kind of tremor it is can be frustrating.
The movement is the symptom. The diagnosis determines the treatment.
Frequently Asked Questions
Does having shaky hands mean I have Parkinson’s disease?
No. Parkinson’s disease is only one cause of tremor. Essential tremor, enhanced physiologic tremor, medications, caffeine, thyroid disease, metabolic abnormalities, dystonia, and other neurologic conditions can all produce shaking.
How common is tremor in Parkinson’s disease?
Approximately 70% to 90% of people with Parkinson’s disease experience tremor at some point during their illness, according to the Parkinson’s Foundation.³ That also means tremor is not universal in Parkinson’s disease.
Can you have Parkinson’s disease without shaking?
Yes. Tremor is not required. Current MDS criteria define parkinsonism by bradykinesia plus either rest tremor or rigidity.⁴
What is an isometric tremor?
An isometric tremor is an action tremor that appears when muscles contract against a rigid stationary object or resistance without purposeful movement—for example, while pushing firmly against a wall or maintaining force against a fixed object.
Why does my hand shake only when I squeeze or push something?
One possibility is an isometric tremor. Other possibilities include task- or position-specific tremor, dystonic tremor, enhanced physiologic tremor, and, less commonly, a peripheral nerve problem. The precise activation pattern and neurologic examination help distinguish among these possibilities.
Can a pinched or entrapped nerve cause tremor?
It appears to be possible but is uncommon. Focal tremor has been reported with peripheral nerve lesions or entrapment. Associated pain, numbness, tingling, weakness, or findings in the distribution of a particular nerve would make this possibility more relevant.
What is the difference between essential tremor and Parkinsonian tremor?
Essential tremor is typically an action tremor, becoming apparent while maintaining a posture or performing movement. The classic Parkinsonian tremor is predominantly a rest tremor and frequently begins asymmetrically. There can be overlap, so diagnosis should not be made from tremor alone.
Can stress cause tremor?
Stress and anxiety can substantially amplify normal physiologic tremor and worsen many established tremor disorders. That does not necessarily mean the tremor is psychological.
Can caffeine cause shaking?
Yes. Caffeine can enhance physiologic tremor, particularly at higher doses or in people who are sensitive to stimulants.
Can medications cause tremor?
Yes. Numerous medications can produce or worsen tremor. Medication and supplement review should therefore be part of a proper evaluation.
When should I worry about a tremor?
A sudden tremor associated with weakness, speech difficulty, severe imbalance, confusion, severe headache, loss of consciousness, or another acute neurologic change warrants prompt evaluation. A gradually progressive tremor should also be evaluated when it interferes with daily activities or occurs with other neurologic changes.
Bottom Line
A tremor is an involuntary, rhythmic, oscillatory movement. But that definition is only the beginning.
The more useful questions are: When does it occur? Where does it occur? What activates it? What makes it stop? Is it present at rest, while holding a position, during movement, or while contracting against resistance? Did it begin suddenly or gradually? Is it symmetric? What other neurologic findings accompany it?
And perhaps most importantly: Tremor does not automatically mean Parkinson’s disease.
Although approximately 70% to 90% of people with Parkinson’s disease experience tremor sometime during their illness, some do not.³ Likewise, many people who have tremor do not have Parkinson’s disease.
Some tremor represents an exaggerated version of normal physiology. Some comes from essential tremor. Some appears only during a specific task, position, or isometric contraction. Some is medication-related or metabolic. Some reflects Parkinson’s disease, dystonia, cerebellar dysfunction, peripheral nerve disease, or another neurologic disorder.
The shaking gets our attention. The circumstances under which it occurs often help tell us why it is happening.
Continue Your Journey to Better Health
Symptoms such as tremor demonstrate why a diagnosis should emerge from the complete clinical picture rather than from one symptom alone. At Stages of Life Medical Institute, our approach is to consider the history, examination, medications, metabolic health, vascular risk factors, nutrition, sleep, and other physiologic systems that may contribute to a patient’s symptoms.
When One Diagnosis Follows You Everywhere: The Value of an Independent Second Opinion
When a diagnosis does not fully explain the clinical picture—or when symptoms evolve differently than expected—an independent evaluation provides another opportunity to examine the evidence from the beginning.
Become a Patient
If you have developed a new or progressive tremor—or have been given a diagnosis of essential tremor or Parkinson’s disease but still have questions about the pattern or possible contributing factors—a comprehensive evaluation can help characterize the movement and identify potentially treatable contributors. 407-679-3337
References
1. Bhatia KP, Bain P, Bajaj N, et al. Consensus Statement on the classification of tremors. From the Task Force on Tremor of the International Parkinson and Movement Disorder Society. Mov Disord. 2018;33(1):75-87. PMID: 29193359. Direct link
2. Haubenberger D, Hallett M. Essential Tremor. N Engl J Med. 2018;378(19):1802-1810. PMID: 29742376. Direct link
3. Parkinson’s Foundation. Tremor. Understanding Parkinson’s: Movement Symptoms. Approximately 70%-90% of people with Parkinson’s disease experience tremor at some point during their illness. Direct link
4. Postuma RB, Berg D, Stern M, et al. MDS clinical diagnostic criteria for Parkinson’s disease. Mov Disord. 2015;30(12):1591-1601. PMID: 26474316. Direct link
5. Shanker V. Essential tremor: diagnosis and management. BMJ. 2019;366:l4485. PMID: 31383632. Direct link
Medical Disclaimer
This article is intended for educational purposes only and does not substitute for individualized medical diagnosis or treatment. Tremor may have neurologic, metabolic, medication-related, peripheral nerve, toxic, or other causes. New, progressive, or unexplained tremor should be evaluated in the context of the individual’s medical history, medications, examination findings, and associated symptoms. Sudden neurologic symptoms may require urgent medical evaluation.
© 2026 Stages of Life Medical Institute
The medical references cited in this article are provided for educational purposes only and are intended to support general scientific discussion. They are not a substitute for individualized medical advice, diagnosis, or treatment. Clinical decisions should always be made in consultation with a qualified healthcare professional who can account for a patient’s unique medical history, medications, and circumstances.
1917 Boothe Circle, Suite 171
Longwood, Florida 32750
Tel: 407-679-3337
Fax: 407-678-7246
.webp)