Trembling: Why You Feel Shaky

Trembling vs tremor

Trembling is the everyday word for shaking. A tremor is the medical term for a rhythmic, involuntary, back-and-forth movement of a body part. Everyone has a tiny normal tremor (physiological tremor), too small to see. Adrenaline, caffeine and other triggers can amplify it so it becomes visible.

Doctors classify tremor by when it happens:

Common causes of trembling

Anxiety, fear and stress

Adrenaline released in fear, anxiety or panic causes shaking, a racing heart, sweating and fast breathing. It stops when the stress settles. Some people with anxiety describe constant "internal trembling", a feeling of vibration inside without visible shaking.

Caffeine, nicotine and stimulants

Coffee, energy drinks, pre-workout supplements, decongestants, nicotine and stimulant drugs such as cocaine and amphetamines amplify physiological tremor.

Low blood sugar

Hypoglycemia causes shaking, sweating, hunger, a fast heartbeat and irritability. It is most common in people taking insulin or sulfonylureas, but can follow alcohol, intense exercise or skipped meals. If you have diabetes, check your sugar and treat a low reading with fast-acting sugar.

Cold and fever

Shivering generates heat. Shaking chills (rigors) during fever suggest infection. See chills.

Fatigue and lack of sleep

Tiredness amplifies physiological tremor.

Medicines

Many drugs cause or worsen tremor, including:

• asthma inhalers such as albuterol (salbutamol)
• lithium and valproate
• some antidepressants
• thyroid hormone at too high a dose
• steroids
• some immune-suppressing drugs such as tacrolimus
• antipsychotics and metoclopramide (which can cause a Parkinson-like tremor)

Persistent causes

Essential tremor

Essential tremor is the most common movement disorder. It causes shaking of both hands when holding something or doing a task, such as drinking from a cup or writing. The head ("yes-yes" or "no-no") and voice can also shake. It often runs in families, often improves temporarily with a small amount of alcohol, and gradually progresses with age.

Overactive thyroid

Hyperthyroidism causes a fine tremor of the outstretched hands, with weight loss despite a good appetite, a racing heart, sweating, heat intolerance, anxiety and loose stools.

Alcohol withdrawal

Alcohol withdrawal causes shaking ("the shakes") 6 to 24 hours after the last drink in people who drink heavily, with sweating, anxiety and nausea. It can progress to seizures or delirium tremens, so medical supervision is needed for withdrawal.

Parkinson's disease

Parkinson's disease often starts with a resting tremor in one hand, sometimes described as "pill-rolling", along with slowness, stiffness, smaller handwriting, reduced arm swing and a quieter voice. The tremor usually lessens when the hand moves.

Other neurological causes

Multiple sclerosis, stroke affecting the cerebellum, dystonia, and nerve damage can cause tremor, usually with other signs.

Clues from other symptoms

How doctors find the cause

A doctor will ask when the shaking happens, which body parts are involved, how long it has been present, family history, caffeine and alcohol use, and medicines. They will observe the tremor at rest, with arms outstretched and during movements such as finger-to-nose testing, ask you to write and draw a spiral, and check for slowness, stiffness and balance problems.

Tests may include:

• thyroid function
• blood sugar, kidney and liver tests, calcium and magnesium
• drug levels, such as lithium
• in selected cases, a brain MRI or a DaT scan to support a Parkinson's diagnosis

Treatment

Treating triggers

• reduce caffeine and energy drinks
• eat regularly, and manage blood sugar in diabetes
• improve sleep
• review medicines with your doctor
• stop smoking and avoid stimulants
• manage stress with breathing exercises, exercise and therapy

Medical treatments

• Essential tremor: propranolol or primidone. Botulinum toxin injections for head or voice tremor. Deep brain stimulation or focused ultrasound for severe disabling tremor.
• Hyperthyroidism: beta blockers for symptoms, then antithyroid medicines, radioactive iodine or surgery.
• Parkinson's disease: levodopa and other dopamine medicines.
• Anxiety: CBT and, if needed, medicines such as SSRIs.
• Alcohol withdrawal: supervised medical detox.

Practical tips

• use heavier cups, weighted utensils and wrist weights
• use both hands to steady a drink
• choose wider pens and voice-to-text tools

Frequently asked questions

Why am I shaking for no reason?

Shaking without an obvious cause is often due to anxiety, caffeine, low blood sugar, tiredness or a medicine side effect. If it persists for weeks, comes with weight loss and a racing heart, or is worse at rest in one hand, see a doctor to check for thyroid problems or a tremor disorder.

What causes shaky hands?

Common causes are anxiety, caffeine, low blood sugar, lack of sleep, and medicines such as asthma inhalers. Essential tremor, an overactive thyroid, alcohol withdrawal and Parkinson's disease cause persistent shaky hands. The pattern of the tremor helps tell them apart.

Is trembling a sign of anxiety?

Yes. Anxiety and panic release adrenaline, which causes trembling, a racing heart, sweating and fast breathing. Some people feel internal trembling without visible shaking. If anxiety is causing frequent shaking, talking therapy and stress management can help.

When should I worry about trembling?

Get urgent help for shaking with confusion, high fever, stiffness, sudden weakness or seizures. See a doctor soon for a tremor that is new, persistent, worsening, one-sided at rest, or interfering with daily tasks.

Can low blood sugar cause trembling?

Yes. Low blood sugar triggers adrenaline release, causing shaking, sweating, hunger, a fast heartbeat and irritability. In people with diabetes, check your blood sugar and treat a low reading with fast-acting sugar, then eat a snack.