Causes

Drug-induced tremor is a simple nervous system and muscle response to certain medications. Drugs that can cause tremor include the following:

• Anticonvulsants such as valproic acid (Depakote), and sodium valproate (Depakene)
• Bronchodilators such as theophylline and albuterol
• Immunosuppressants such as cyclosporine
• Mood stabilizers such as lithium carbonate
• Stimulants such as caffeine

Symptoms

The tremor may affect the hands, arms, head, or eyelids. It rarely affects the lower body and may not affect both sides of the body equally.

The shaking is usually fast, at about 6 to 10 movements per second.

The tremor may be:

• Episodic (occurring in bursts, sometimes about an hour after taking the medication)
• Intermittent (comes and goes with activity, but not always)
• Sporadic (occasional)

The tremor can:

• Disappear during sleep
• Get worse with voluntary movement and emotional stress

Other symptoms may include:

• Head nodding
• Shaking or quivering sound to your voice

Exams and Tests

Your doctor can make the diagnosis by performing a physical exam and asking questions about your medical and personal history, especially your medication use.

A physical exam will show shaking with movement. There are usually no problems with coordination or mental function.

Other tests are usually not needed. However, further tests may be done to rule out other reasons for the tremor. A tremor that occurs when the muscles are relaxed or that affects the legs or coordination may be a sign of another condition, such as Parkinson's disease. The speed of the tremor can be an important way to determine its cause.

Other causes of tremors may include:

• Alcohol withdrawal
• Cigarette smoking
• Hyperthyroidism
• Parkinson's disease
• Pheochromocytoma
• Too much caffeine
• Wilson's disease

Blood tests and imaging studies (such as a CT scan of the head, brain MRI, and x-rays) are usually normal.

Treatment

Drug-induced tremor will go away when you stop taking the medicine that is causing the shaking.

You may not need treatment or changes in medications if the tremor is mild and does not interfere with your daily activity.

If the benefit of the medicine is greater than the problems caused by the tremor, you may try different doses or types of medicines. Different doses or similar medications may not cause the tremor.

In rare cases, a drug such as inderal (Propanalol) or mysoline (Primidone) may be added to help control the tremor. You may take one of these medications if you cannot stop taking the drug that is causing the tremor.

Never stop taking any medicine without first talking to your doctor.

Outlook (Prognosis)

Drug-induced tremor is not a dangerous condition, but some patients find the tremor annoying and embarrassing.

Possible Complications

Severe tremor can interfere with daily activities, especially fine motor skills such as writing, and other activities such as eating or drinking.

When to Contact a Medical Professional

Call your health care provider if you are taking a medication and a tremor develops that interferes with your activity or is accompanied by other symptoms.

Prevention

Always tell your doctor about the medicines you take. Take over-the-counter drugs with caution, especially those that contain stimulants or a medicine called theophylline.

Caffeine can cause tremor and make tremor caused by other medications worse. Avoid caffeinated drinks such as coffee, tea, and soda. Also avoid other stimulants if you have tremor.

Alternative Names

Tremor - drug-induced

References

Elble RJ. Tremor: Clinical features, pathophysiology, and treatment. Neurol Clin. 2009;27:679-695.

Jankovic J, Lang AE. Movement disorders: Diagnosis and assessment. In: Bradley WG, Daroff RB, Fenichel GM, Jankovic J, eds. Neurology in Clinical Practice. 5th ed. Philadelphia, Pa: Butterworth-Heinemann; 2008:chap 23.

Lang A. Other movement disorders. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 434.

Update Date: 4/29/2012

Reviewed by: Linda Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington School of Medicine; and Daniel B. Hoch, PhD, MD, Assistant Professor of Neurology, Harvard Medical School, Department of Neurology, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.