Drug-Induced Movement Disorders

Overview

Drug-induced movement disorders are abnormal movements that develop as a side effect of certain medications. They most often occur with drugs that block or alter dopamine, a brain chemical that helps control movement. These include some antipsychotic medications and certain drugs used to treat nausea and stomach problems.

The movements can take several forms, from a Parkinson-like tremor and stiffness to inner restlessness, sustained muscle contractions, or repetitive involuntary movements. Some appear soon after starting a medication, while others develop after months or years of use. Recognizing that a medication is the cause is important, because adjusting or changing the drug, when it can be done safely, often improves or reverses the symptoms.

Symptoms

Drug-induced movement disorders include several distinct patterns, and a person may have one or more:

• Drug-induced parkinsonism: Tremor, stiffness, slow movement, and a shuffling walk, resembling Parkinson's disease.
• Akathisia: A distressing feeling of inner restlessness and an inability to stay still.
• Acute dystonia: Sudden, sustained muscle contractions causing twisting postures, often of the neck, eyes, or jaw, usually soon after starting a medication.
• Tardive dyskinesia: Repetitive involuntary movements, often of the face, lips, and tongue, that develop after long-term use.
• Tremor: Shaking that can occur with several medications.

A rare but serious reaction called neuroleptic malignant syndrome causes high fever, severe muscle stiffness, confusion, and unstable vital signs. This is a medical emergency requiring immediate care.

Causes

These disorders are caused by medications that affect the brain's movement-control systems, most commonly by blocking dopamine. Drugs that can cause them include:

• Antipsychotic medications used for psychiatric conditions, especially older agents.
• Certain anti-nausea and gastrointestinal drugs that block dopamine.
• Some antidepressants and mood stabilizers, which can cause tremor.
• Certain other medications that influence brain chemistry.

The risk depends on the specific drug, the dose, how long it is taken, and individual factors. Not everyone who takes these medications develops a movement disorder.

Risk Factors

• Use of dopamine-blocking medications, especially at higher doses or long term
• Older age
• Female sex for some types, such as tardive dyskinesia
• Use of more than one medication that affects movement
• Pre-existing brain or neurological conditions

Diagnosis

Diagnosis relies on recognizing the pattern of movements and linking it to a medication. A doctor will:

• Review all current and recent medications, including doses and timing
• Examine the type and distribution of the abnormal movements
• Consider how the timing relates to starting, changing, or stopping a drug
• Rule out other causes such as Parkinson's disease or other neurological conditions

Tests are sometimes used to exclude other causes, but the diagnosis is mainly clinical, based on the relationship between the medication and the movements.

Treatment

Treatment centers on adjusting the responsible medication whenever this can be done safely, along with specific measures for each type of movement.

• Medication review: Lowering the dose, switching to a drug less likely to cause movement problems, or stopping the medication, always under medical supervision.
• Acute dystonia: Often responds quickly to specific medicines given promptly.
• Akathisia: May improve with dose changes or certain medications that reduce restlessness.
• Tardive dyskinesia: Specific treatments are available; early recognition gives the best chance of improvement.
• Never stop psychiatric medication abruptly on your own, as this can be harmful; changes should be made with your prescriber.

Many drug-induced movements improve when the medication is adjusted, though some, such as tardive dyskinesia, can persist.

Prevention

• Use medications that affect dopamine at the lowest effective dose and for the shortest needed time
• Have regular reviews of long-term medications and report new movements early
• Tell your doctor about any past reactions to these medicines
• Do not stop or change prescribed medication without medical advice

When to See a Doctor

See your doctor if you develop new tremor, stiffness, restlessness, or involuntary movements after starting or changing a medication. Seek emergency care for sudden severe muscle spasms affecting breathing or swallowing, or for high fever with severe muscle stiffness, confusion, and a racing heart, which may indicate neuroleptic malignant syndrome, a life-threatening reaction.

Related Topics

Frequently Asked Questions

References

1. National Institute of Neurological Disorders and Stroke (NINDS). Movement disorders.
2. MedlinePlus, U.S. National Library of Medicine. Drug-induced tremor and movement disorders.
3. U.S. Food and Drug Administration (FDA). Tardive dyskinesia.
4. Mayo Clinic. Drug-induced parkinsonism and tardive dyskinesia.