Akathisia: the drug side effect that feels unbearable

What akathisia is

Akathisia (from the Greek meaning "unable to sit") is a movement-adjacent side effect defined by two things: a subjective sense of inner restlessness, and observable motor manifestations like pacing, foot-tapping, shifting weight, and inability to sit still. The subjective component is the harder part. Patients describe it as feeling "wired," "like my skin is crawling from the inside," "like I need to jump out of my skin." It is one of the most distressing psychiatric side effects, and it has been directly linked to suicide attempts and completed suicides in the schizophrenia and mood-disorder literature.

Akathisia sits on a spectrum with related movement disorders. Acute akathisia occurs within days to weeks of starting or increasing a causative drug. Tardive akathisia can develop after months to years of exposure, similar to tardive dyskinesia. Chronic akathisia describes symptoms persisting more than 6 months. Each has a slightly different management approach.

Which drugs cause akathisia

Antipsychotics are the most common cause. Among first-generation drugs, haloperidol and fluphenazine cause it most often; chlorpromazine and thioridazine less so. Among second-generation drugs, risperidone and paliperidone cause it often, aripiprazole causes a distinctive "activation" pattern that overlaps with akathisia (especially at initiation), and olanzapine, quetiapine, and clozapine cause it less often. Lurasidone has been reported to cause akathisia at moderate rates. Cariprazine and brexpiprazole have signals for akathisia as partial agonists.

Antidepressants, especially SSRIs and SNRIs, cause akathisia less commonly but not rarely. Fluoxetine and paroxetine are the SSRIs most cited. Venlafaxine and duloxetine cause it too. The mechanism is thought to be indirect dopamine modulation via serotonin.

Metoclopramide (Reglan) is a non-psychiatric drug that causes akathisia frequently. It is a dopamine D2 antagonist used for gastroparesis and nausea. Patients on metoclopramide who develop restlessness are commonly misdiagnosed with anxiety when the diagnosis is akathisia.

Aripiprazole deserves specific attention because its activation profile at initiation is often called "aripiprazole activation" or "aripiprazole-induced akathisia." It presents like classic akathisia and responds to the same treatments. Some patients tolerate it better if aripiprazole is started at a lower dose (2 mg) and titrated up slowly.

How to recognize it

Three features distinguish akathisia from anxiety:

1. The motor picture: pacing, foot-tapping, shifting in the chair, unable to sit still even briefly. Anxious patients are also fidgety, but the compulsive quality of akathisia is different.
2. The temporal relationship: onset within days to weeks of starting or increasing the causative drug. If you cannot map the symptom onset to a medication change, akathisia is less likely.
3. The patient description: "I feel like I need to move" or "I can't sit still" more than "I'm worried" or "I'm scared." Anxious patients describe cognitive worry; akathisia patients describe physical need to move.

The Barnes Akathisia Rating Scale is the standard clinical instrument. It scores objective observation, subjective awareness, subjective distress, and global clinical assessment. Scoring is quick and helpful for tracking response to treatment.

Misdiagnosis is common. The classic error is calling akathisia "anxiety" or "agitation" in a psychotic patient and increasing the antipsychotic dose, which makes akathisia worse and worsens the misinterpretation.

Management

The core principle: reduce or remove the causative drug when possible. Everything else is symptomatic control while that happens.

Dose reduction or drug change: If the antipsychotic dose can be reduced or switched to a lower-akathisia-risk drug (olanzapine, quetiapine, clozapine), that is the definitive intervention. This is not always possible; some patients need the specific drug for symptom control.

Beta-blockers: Propranolol 20 to 40 mg twice or three times daily is the most-cited first-line agent. Its efficacy is best supported. Onset is over days. Contraindicated in asthma, uncontrolled heart failure, and severe bradycardia.

Benzodiazepines: Clonazepam 0.5 to 2 mg per day or lorazepam 1 to 2 mg TID are widely used. Onset is rapid. Watch for sedation and dependence risk.

Anticholinergics: Benztropine 1 to 2 mg twice daily or diphenhydramine 25 to 50 mg two or three times daily. Better for other extrapyramidal symptoms than for pure akathisia, but sometimes helpful. Adds anticholinergic burden which matters in elderly patients.

Mirtazapine or mianserin: 15 to 30 mg has been reported to help akathisia via 5-HT2A antagonism. Considered when other agents fail.

Serotonin 5-HT2A antagonists (cyproheptadine, trazodone) have been reported but are less well studied.

Vitamin B6 (pyridoxine) at high doses (600 to 1200 mg/day) has small trial evidence and is generally safe.

Refractory akathisia sometimes responds to switching to clozapine, which has the lowest akathisia rate among antipsychotics.

Epidemiology and clinical impact

Acute akathisia occurs in roughly 20 to 40 percent of patients started on first-generation antipsychotics and 10 to 20 percent of patients on second-generation antipsychotics. Aripiprazole activation rates approach 30 percent in some initiation studies. Rates vary by drug, dose, and patient.

The clinical impact is substantial. Akathisia is a leading cause of antipsychotic non-adherence. It has been independently associated with suicidal ideation and completed suicide across multiple case series and observational studies. Van Putten's classic 1974 paper described how patients with akathisia frequently refuse further medication or leave treatment entirely. This has held up in subsequent research.

Common questions

Is akathisia dangerous? The physical side effect itself is not directly life-threatening, but the associated distress can be. Akathisia has been linked to suicidal ideation and completed suicides in the literature. It also frequently causes patients to stop their medication entirely, which can precipitate psychosis relapse or mood decompensation. Recognition and treatment are both important.

Does akathisia go away when the drug is stopped? Usually yes, within days to weeks, for acute akathisia. Tardive akathisia (developing after prolonged exposure) can persist for months or years even after the drug is stopped, similar to tardive dyskinesia.

Which antipsychotic has the lowest akathisia risk? Clozapine consistently has the lowest rates. Quetiapine and olanzapine are lower than risperidone and haloperidol. Newer options like Cobenfy (xanomeline-trospium), which does not block D2 receptors, avoid dopaminergic movement side effects including akathisia entirely.

Can SSRIs really cause akathisia? Yes, though less commonly than antipsychotics. SSRI-induced akathisia most often occurs in the first 1 to 4 weeks of treatment. Fluoxetine and paroxetine are the most-cited offenders in the SSRI class. Discontinuation resolves the akathisia; if the SSRI is still needed, switching to a different SSRI or adding a beta-blocker is standard.

Is akathisia the same as anxiety? No. Akathisia is a distinct movement disorder with characteristic motor manifestations and a specific subjective experience of physical restlessness. Anxiety is a psychiatric symptom with worry, autonomic activation, and cognitive-emotional components. The overlap in presentation is why misdiagnosis is common, but the mechanisms and treatments are different.

How long does akathisia take to resolve after treatment? With dose reduction or drug switch, most acute akathisia resolves within 1 to 4 weeks. Beta-blockers and benzodiazepines can produce noticeable improvement within days. Tardive akathisia can persist for months to years.

Is there a specific test for akathisia? The Barnes Akathisia Rating Scale is the standard clinical instrument. There is no lab test or imaging test. Diagnosis is clinical.

Sources

• Barnes TR. A rating scale for drug-induced akathisia. Br J Psychiatry. 1989;154:672-676.
• Van Putten T. The many faces of akathisia. Compr Psychiatry. 1975;16(1):43-47.
• Poyurovsky M. Acute antipsychotic-induced akathisia revisited. Br J Psychiatry. 2010;196(2):89-91.
• Miller CH, Fleischhacker WW. Managing antipsychotic-induced acute and chronic akathisia. Drug Saf. 2000;22(1):73-81.
• Salem H, Nagpal C, Pigott T, Teixeira AL. Revisiting antipsychotic-induced akathisia: current issues and prospective challenges. Curr Neuropharmacol. 2017;15(5):789-798.
• Lohr JB, Eidt CA, Abdulrazzaq Alfaraj A, Soliman MA. The clinical challenges of akathisia. CNS Spectr. 2015;20 Suppl 1:1-14.