EPS stands for extrapyramidal symptoms, a group of movement-related side effects caused by antipsychotic medications and certain other drugs used in mental health treatment. These side effects happen because the medications block dopamine receptors in parts of the brain that control voluntary movement, not just the parts involved in psychiatric symptoms. EPS can range from mild restlessness to involuntary muscle contractions, and they’re one of the most common reasons people struggle to stay on their psychiatric medications.
How Antipsychotics Cause Movement Problems
Antipsychotic medications work by blocking dopamine receptors in the brain. That’s what helps reduce symptoms like hallucinations, delusions, and disorganized thinking. But dopamine doesn’t just regulate mood and perception. It also plays a central role in coordinating smooth, controlled movement through a network of brain structures called the basal ganglia.
When an antipsychotic blocks dopamine receptors in these movement-related areas, the brain loses some of its ability to fine-tune muscle activity. The result is a range of involuntary movements, stiffness, or restlessness that falls under the EPS umbrella. Older antipsychotics (sometimes called first-generation or “typical” antipsychotics) are more likely to cause EPS because they block dopamine receptors more broadly and aggressively. Newer, second-generation antipsychotics were designed to be more selective, but they can still cause EPS, particularly at higher doses.
The Four Main Types of EPS
Acute Dystonia
Dystonia involves sudden, sustained muscle contractions that force parts of the body into abnormal positions. This might look like the neck twisting to one side, the jaw locking open, or the eyes rolling upward. It tends to appear early, often within the first few days of starting a medication or increasing a dose. Dystonia can be frightening, but it typically responds quickly to treatment. Men under 65 are at higher risk for this type.
Akathisia
Akathisia is an intense inner restlessness that makes it nearly impossible to sit still. People describe it as feeling like they need to pace, shift their weight, or keep moving constantly. It’s not just fidgeting. The sensation is deeply uncomfortable and distressing, and it’s one of the most common reasons people stop taking their antipsychotic without telling their prescriber. In studies of people on antipsychotics, akathisia has been observed in anywhere from 5% to over 30% of patients depending on the medication and population.
Drug-Induced Parkinsonism
This type closely resembles Parkinson’s disease: tremor (especially in the hands), muscle rigidity, slowed movement, shuffling gait, and a mask-like facial expression. It develops over weeks to months after starting medication. Research published in The British Journal of Psychiatry found parkinsonism present in over half of patients taking either first- or second-generation antipsychotics, making it one of the most common forms of EPS. Women over 65 face a higher risk.
Tardive Dyskinesia
Tardive dyskinesia (TD) is the most concerning form of EPS because it develops after months or years of medication use, and it can become permanent even after the drug is stopped. It typically involves repetitive, involuntary movements of the face, tongue, and jaw: lip smacking, tongue darting, chewing motions, or grimacing. It can also affect the limbs and trunk. In the same British Journal of Psychiatry study, new cases of tardive dyskinesia appeared in roughly 4% to 8% of patients over a year-long follow-up, with no significant difference between older and newer antipsychotics. Women over 65 are also at elevated risk for TD.
Who Is Most at Risk
Several factors increase the likelihood of developing EPS. Higher medication doses carry more risk, as do first-generation antipsychotics compared to newer ones. If you’ve experienced EPS before, you’re more likely to experience it again with a new medication or dose change. Age and sex also play a role: women over 65 are more vulnerable to parkinsonism and tardive dyskinesia, while younger men are more prone to dystonia. A prior history of EPS is itself a risk factor, suggesting some people have a lower individual threshold for these side effects.
How EPS Is Identified
Clinicians use structured rating scales to screen for and monitor EPS. The most widely used tool for tardive dyskinesia is the Abnormal Involuntary Movement Scale (AIMS), a 12-item assessment that rates involuntary movements across different body regions on a scale from zero (none) to four (severe). The first seven items evaluate specific movements in the face, extremities, and trunk, while the remaining items address overall severity and dental health, since oral movements can sometimes be mistaken for dental problems.
Regular screening matters because tardive dyskinesia in particular can develop gradually, and people sometimes don’t notice the early movements themselves. Catching it early gives prescribers the best chance to adjust treatment before the symptoms become harder to reverse.
How EPS Is Managed
The first step is usually adjusting the medication causing the problem. That might mean lowering the dose or switching to an antipsychotic with a lower EPS risk. For some people, this alone resolves the symptoms.
When the antipsychotic can’t be changed (because it’s effectively treating the psychiatric condition), additional medications can be added to counteract the movement symptoms. Anticholinergic medications like benztropine are commonly used for acute dystonia and parkinsonism. For akathisia, beta-blockers such as propranolol, certain anti-anxiety medications, or specific antidepressants may help. Acute dystonia often responds rapidly to treatment, sometimes within minutes of receiving medication.
Tardive dyskinesia is harder to treat. If the antipsychotic can be safely tapered off, symptoms may improve over time, though not always. Some people with TD have responded to anticholinergic therapy, and in cases where antipsychotic treatment must continue, switching to a specific antipsychotic with a different receptor profile has shown benefit in case reports. Newer medications designed specifically for tardive dyskinesia have also become available in recent years, giving people more options than existed a decade ago.
Why EPS Matters for Mental Health Treatment
EPS is one of the biggest obstacles to staying on psychiatric medication. Akathisia feels unbearable for many people. Parkinsonism can be physically limiting and socially isolating. Tardive dyskinesia is visible to others and carries significant stigma. All of these side effects can make someone feel like the treatment is worse than the illness, leading them to stop medication abruptly, which in turn raises the risk of psychiatric relapse.
If you’re experiencing involuntary movements, unusual stiffness, tremor, or an overwhelming urge to keep moving after starting or changing a psychiatric medication, these are recognized and treatable side effects. They don’t mean the medication is “wrong” for you in every case, but they do mean your treatment plan likely needs adjustment. The earlier EPS is identified, the more options are available and the better the outcomes tend to be.