What does EPS stand for extrapyramidal symptoms? A pharmacological overview

October 11, 2025 •

3 min read

Over 20% of people on antipsychotics develop movement disorders known as extrapyramidal symptoms (EPS). These are side effects that arise from certain medications, particularly those that block dopamine receptors in the brain.

Quick Summary

Extrapyramidal symptoms, or EPS, are a range of movement disorders caused by certain medications, most commonly antipsychotic drugs. They result from dopamine pathway disruption and manifest as involuntary movements, muscle rigidity, and restlessness. Management involves adjusting the medication or adding other drugs to alleviate the motor side effects.

Key Points

Acronym Definition: EPS stands for Extrapyramidal Symptoms, drug-induced movement disorders affecting involuntary control.
Primary Cause: Most commonly caused by antipsychotic medications blocking dopamine receptors.
Spectrum of Symptoms: Includes acute dystonia, akathisia, pseudoparkinsonism, and tardive dyskinesia.
Antipsychotic Risk: First-generation antipsychotics have higher risk; atypical antipsychotics have lower risk but still pose some risk.
Management Strategies: Involve medication adjustment, switching drugs, or adding medications to manage symptoms.
Chronic vs. Acute: Acute EPS can be reversible; tardive dyskinesia can be persistent or permanent.
Life-Threatening Risk: Neuroleptic Malignant Syndrome (NMS) is a rare, severe, potentially fatal drug reaction.

What is the Extrapyramidal System?

To understand what does EPS stand for extrapyramidal symptoms, it is crucial to first grasp the extrapyramidal system itself. This is a network of nerve cells in the brain that helps regulate and coordinate involuntary movements, posture, and muscle tone. It is distinct from the pyramidal tract, which controls voluntary movement. The extrapyramidal system primarily relies on the basal ganglia and dopamine neurotransmission to function properly. When this delicate balance is disrupted, particularly by drugs that block dopamine receptors, a range of movement disorders can appear.

Medications that Cause Extrapyramidal Symptoms

Extrapyramidal symptoms are most famously associated with first-generation (or typical) antipsychotic medications, such as haloperidol and chlorpromazine. These drugs are potent dopamine D2 receptor blockers, and their effects on the nigrostriatal dopamine pathway are the primary cause of EPS. While second-generation (atypical) antipsychotics carry a lower risk, they are not without risk, especially at higher doses. Other medications, including some anti-nausea drugs, antidepressants, mood stabilizers, and stimulants, can also induce these side effects.

Types of Extrapyramidal Symptoms

EPS can be categorized into four main types:

Acute Dystonia

Onset: Typically occurs within hours or days of starting a new medication or increasing the dose.
Symptoms: Sudden, sustained, and often painful muscle contractions or spasms.
Key Feature: Can be frightening and distressing due to sudden, involuntary nature.

Akathisia

Onset: Can occur acutely or develop later.
Symptoms: A profound sense of inner restlessness or the irresistible urge to move.
Key Feature: Considered one of the most subjectively distressing types of EPS and often mistaken for anxiety.

Pseudoparkinsonism

Onset: Usually develops gradually over days to weeks.
Symptoms: Mimics Parkinson's symptoms: tremors at rest, muscle rigidity, slowed movements, shuffling gait.
Key Feature: Often includes a mask-like facial expression and stooped posture.

Tardive Dyskinesia (TD)

Onset: Delayed-onset, typically appearing after months or years of continuous use.
Symptoms: Involuntary, repetitive movements, often involving the face, limbs, or trunk.
Key Feature: A chronic condition; can be permanent even after stopping the medication.

A Comparison of Antipsychotic Types and EPS Risk

To help illustrate why atypical antipsychotics are often preferred, here is a comparison of typical versus atypical antipsychotics regarding their mechanism and risk of EPS.


Feature	Typical Antipsychotics (e.g., Haloperidol)	Atypical Antipsychotics (e.g., Risperidone, Quetiapine)
Mechanism of Action	Primarily strong blockers of dopamine D2 receptors.	Block both dopamine D2 and serotonin 5-HT2A receptors.
Risk of EPS	High risk, especially with higher doses and long-term use.	Lower risk compared to typical antipsychotics due to their broader mechanism of action.
Tardive Dyskinesia Risk	Higher risk, particularly over long periods of treatment.	Reduced risk, making them preferable for long-term therapy.
Metabolic Side Effects	Lower risk of metabolic issues like weight gain and diabetes.	Higher risk of metabolic side effects, including weight gain, lipid abnormalities, and diabetes.
Treatment for Psychosis	Highly effective for managing positive symptoms of schizophrenia (e.g., hallucinations, delusions).	Effective for both positive and negative symptoms of schizophrenia (e.g., apathy, blunted affect).

Treatment and Management of EPS

Managing extrapyramidal symptoms requires adjusting or stopping the causative medication. Switching to a medication with lower EPS risk, like an atypical antipsychotic, may be an option if treatment is necessary.

Treatments vary by EPS type:

Acute Dystonia and Pseudoparkinsonism: Anticholinergic drugs like benztropine or trihexyphenidyl are common. In acute cases, an injection of diphenhydramine can provide rapid relief.
Akathisia: Beta-blockers, such as propranolol, are often first-line. Benzodiazepines may also be used.
Tardive Dyskinesia: This is challenging to treat. Options include VMAT2 inhibitors (valbenazine, deutetrabenazine) or switching to clozapine. Deep brain stimulation may be considered for severe cases.

Conclusion

Understanding extrapyramidal symptoms is vital for individuals taking or prescribing certain medications. These drug-induced movement disorders impact quality of life and depend on medication type, with older antipsychotics carrying higher risk. Early detection and management, including dose changes, medication switching, or additional drugs, are essential for minimizing impact. While acute symptoms are often reversible, chronic conditions like tardive dyskinesia highlight the need for vigilance. Patients should discuss any new movements or restlessness with healthcare providers for prompt treatment.

For additional information on managing drug-induced movement disorders, consult your healthcare provider or a specialist in movement disorders.

Frequently Asked Questions

The extrapyramidal system is a network of nerves and brain structures, primarily involving the basal ganglia, that controls involuntary movements, posture, and muscle tone.

First-generation antipsychotics, such as haloperidol, have the highest risk. Certain anti-nausea drugs, like metoclopramide, and some antidepressants can also cause EPS.

Acute dystonia involves sudden, severe muscle spasms that occur shortly after starting a medication. Tardive dyskinesia is a delayed side effect, causing repetitive, involuntary movements often in the face, that develops after prolonged medication use.

While many acute EPS are reversible, tardive dyskinesia, in particular, can become permanent even after the causative medication is stopped. Early treatment lowers the risk of symptoms becoming chronic.

The first step is often to adjust the dosage of the causative medication or switch to a different drug with a lower risk of causing extrapyramidal symptoms.

No, akathisia is a distinct type of EPS defined as an inner sense of restlessness and an uncontrollable need to move. While it can cause agitation, it is a movement disorder and requires different management than anxiety.

NMS is a rare, life-threatening reaction to dopamine-blocking medications characterized by high fever, severe muscle rigidity, altered mental status, and autonomic instability.

Atypical antipsychotics generally have a lower risk of causing EPS compared to first-generation drugs. However, the risk is not eliminated, and it can increase with higher doses.