Tremor: Types, Causes and When to See a Doctor

What a tremor is

A tremor is an oscillation: muscles that pull in opposite directions contract and relax in turn, producing a regular back-and-forth movement. This regular rhythm is what separates tremor from other abnormal involuntary movements such as jerks (myoclonus), twisting postures (dystonia), dance-like movements (chorea) or tics.

Tremor is described by:

• When it happens: at rest, when holding a position, or during movement
• Where it is: hands, head ("yes-yes" or "no-no"), voice, chin, legs or trunk
• Frequency: slow (under 4 beats per second), medium (4 to 7) or fast (over 7)
• Amplitude: fine, barely visible, or coarse and large

Types of tremor

Neurologists divide tremor into two main types, then into subtypes. This is the usual answer to "how many types of tremors are there?": two broad categories and about six commonly named subtypes.

Rest tremor

Occurs when the body part is relaxed and supported, such as the hands resting in the lap. It usually lessens when you move the limb, and returns when you hold a new position. The classic example is the "pill-rolling" tremor of Parkinson's disease, where the thumb rubs against the fingers at 4 to 6 beats per second, often starting on one side.

Action tremor

Occurs when muscles are working. Subtypes:

• Postural tremor: appears when holding a position against gravity, such as arms stretched out in front. Typical of essential tremor, physiological tremor, thyroid overactivity and medicines.
• Kinetic tremor: appears during any voluntary movement, like pouring water or writing.
• Intention tremor: gets worse as the hand approaches a target, as in the finger-to-nose test. It points to a problem in the cerebellum, from multiple sclerosis, stroke, alcohol damage or inherited ataxia.
• Task-specific tremor: appears only during a particular skilled task, such as writing (primary writing tremor) or playing an instrument.
• Isometric tremor: happens when a muscle contracts against something that does not move, such as gripping a heavy bag. Orthostatic tremor, a fast tremor of the legs when standing still, is a rare form that makes people feel unsteady and relieved when they walk or sit.

Types of tremors chart

Causes of tremor

Enhanced physiological tremor

Everyone has a fine, fast tremor that is normally invisible. It becomes noticeable with:

• caffeine, nicotine and energy drinks
• anxiety, fear, anger or stress
• tiredness, lack of sleep and hunger
• intense exercise
• cold
• low blood sugar (hypoglycemia)
• an overactive thyroid (hyperthyroidism), with weight loss, fast pulse and sweating

It is fine, fast and in both hands, mainly when holding them out.

Medicines and substances

Drug-induced tremor is common and often reversible. Culprits include:

• asthma inhalers such as salbutamol (albuterol) and theophylline
• lithium and valproate
• some antidepressants (SSRIs, tricyclics)
• thyroid hormone at too high a dose
• steroids
• antipsychotics and metoclopramide, which can cause a Parkinson-like rest tremor
• stimulants, including ADHD medicines and decongestants
• some transplant and cancer medicines such as tacrolimus and cyclosporine

Withdrawal

Alcohol withdrawal causes a coarse tremor 6 to 24 hours after the last drink, often with sweating, nausea and anxiety. Withdrawal from benzodiazepines or opioids can cause similar shaking.

Essential tremor

Essential tremor is the most common movement disorder. It causes an action tremor of both hands and forearms that worsens slowly over years. It may also affect the head, voice and chin. About half of people with it have a family history. A small amount of alcohol often reduces it temporarily, a well-known clue.

Parkinson's disease

Parkinson's causes a rest tremor in about 70% of people, but tremor alone is not enough for the diagnosis. Other signs are slowness of movement (bradykinesia), stiffness, a shuffling walk, a reduced arm swing, smaller handwriting, softer voice and less facial expression.

Other neurological causes

• Dystonic tremor: irregular tremor in a body part affected by dystonia, for example a jerky head tremor with the neck pulled to one side.
• Cerebellar tremor: an intention tremor with poor coordination, from multiple sclerosis, stroke, tumors, long-term alcohol misuse or cerebellar ataxia.
• Holmes tremor: a slow, coarse tremor at rest, during posture and during movement, after damage to the midbrain from stroke or injury.
• Neuropathic tremor: tremor with peripheral nerve damage.
• Wilson disease: a rare copper disorder in young people, causing a "wing-beating" tremor, liver problems and personality changes.
• Functional tremor: a real, involuntary tremor caused by a problem in how the brain controls movement rather than structural damage. It often starts suddenly, varies in frequency and lessens when attention is distracted.

Essential tremor vs Parkinson's tremor

How doctors diagnose tremor

The diagnosis is mostly made at the bedside. Your doctor will ask when the tremor began, whether it is worse at rest or with movement, what makes it better or worse (alcohol, caffeine, stress), your medicines, alcohol intake and family history. They will watch your hands at rest, held out and during the finger-to-nose test, ask you to draw a spiral and write a sentence, and check your walking, muscle tone and speed of movement.

Tests may include:

• Blood tests: thyroid function, blood sugar, kidney and liver function, calcium, magnesium and drug levels such as lithium
• Copper and ceruloplasmin: in anyone under 50 with an unexplained tremor, to rule out Wilson disease
• MRI of the brain: if there are signs of stroke, MS or a structural cause
• DaTscan: a specialized scan that can help tell Parkinson's disease from essential tremor in uncertain cases
• Electromyography (EMG) or accelerometry: measures tremor frequency, useful for orthostatic or functional tremor

Treatment of tremor

Reduce triggers

• Cut down caffeine and energy drinks.
• Get enough sleep and manage stress.
• Ask your doctor whether any of your medicines could be responsible. Do not stop a prescribed medicine without advice.
• Never use alcohol to control a tremor. Its effect is short-lived, and regular use leads to rebound tremor and dependence.

Practical adjustments

• Use heavier cups, cutlery and pens, or weighted wrist cuffs.
• Hold a cup with both hands, or use a lid and straw.
• Brace your elbows against your body or a table when doing fine tasks.
• Voice-to-text and larger keyboard settings help with typing.
• An occupational therapist can suggest specific aids.

Medicines

• Essential tremor: propranolol (a beta-blocker) and primidone (an anticonvulsant) are the main first-line medicines. Topiramate and gabapentin are alternatives.
• Parkinson's disease: levodopa and other dopamine-boosting medicines treat tremor along with slowness and stiffness.
• Dystonic tremor: botulinum toxin injections into affected muscles.
• Thyroid tremor: treating the thyroid, with a beta-blocker for symptoms in the meantime.

Procedures for severe tremor

• Deep brain stimulation (DBS): thin electrodes placed in the brain connected to a pacemaker-like device. Highly effective for essential tremor and Parkinson's tremor.
• Focused ultrasound thalamotomy: an incision-free procedure guided by MRI that creates a tiny lesion in the thalamus to stop tremor on one side.

Frequently asked questions

How many types of tremors are there?

There are two main types: rest tremor, which happens when muscles are relaxed, and action tremor, which happens when muscles are used. Action tremor includes postural, kinetic, intention, task-specific and isometric tremor. Clinicians then name the syndrome, such as essential tremor, Parkinsonian tremor or cerebellar tremor.

What is involuntary movement called?

The general term is a movement disorder, or dyskinesia. A rhythmic shaking movement is a tremor. Sudden jerks are myoclonus, twisting postures are dystonia, flowing dance-like movements are chorea, and brief repetitive movements or sounds that can be held back briefly are tics.

Is a tremor always a sign of Parkinson's disease?

No. Most tremors are not caused by Parkinson's disease. Enhanced physiological tremor from caffeine, anxiety or medicines, and essential tremor, are far more common. Parkinson's tremor typically happens at rest, starts on one side and comes with slowness and stiffness.

Can anxiety cause a tremor?

Yes. Adrenaline released during anxiety or stress amplifies the normal physiological tremor, causing fine shaking of the hands, often with a racing heart and sweating. It settles as the anxiety passes. A persistent tremor that is present even when you are calm needs a medical review.

When should I worry about a tremor?

See a doctor for any new tremor that persists, worsens or affects daily tasks. Get help urgently if tremor comes with weakness, slurred speech, confusion, fever, rigid muscles, unsteady walking, or after a new medicine or stopping alcohol. These suggest a cause that needs prompt treatment.

Can a tremor be cured?

It depends on the cause. Tremor from caffeine, medicines, low blood sugar or an overactive thyroid usually goes away once the cause is treated. Essential tremor and Parkinson's tremor cannot be cured, but medicines, deep brain stimulation and focused ultrasound can control them well.