What is Akathisia?
Akathisia is a medication-induced movement disorder characterized by both subjective inner restlessness with an urgent need to move and objective motor restlessness, most commonly caused by antipsychotic medications. 1, 2
Core Clinical Features
Akathisia presents with two essential components that distinguish it from other conditions:
- Subjective component: Inner restlessness, emotional unease, anxiety, and a constant compelling urge to move 3, 4
- Objective component: Observable fidgety movements while seated, rocking in place while standing, pacing, lifting feet as if marching on the spot, crossing and uncrossing legs, and inability to sit or stand still for extended periods 4, 5
It is critical to understand that akathisia involves restlessness and an urge to move—not constant pain. 1 If a patient reports constant pain rather than typical restlessness, consider alternative diagnoses such as musculoskeletal pain or dystonia (which involves painful spastic muscle contractions). 1, 2
Causative Medications
The primary culprits causing akathisia include:
- Antipsychotics (most common cause): Prevalence ranges from 5% to 36.8% across different agents 2, 3, 6
- SSRIs, particularly fluoxetine, are well-documented causes 2
Critical Diagnostic Pitfall
Akathisia is frequently misinterpreted as psychotic agitation or anxiety, leading clinicians to inappropriately increase antipsychotic doses, which worsens the condition. 7, 2, 4 This misdiagnosis can have devastating consequences, including poor medication adherence, exacerbation of psychiatric symptoms, aggression, violence, and suicide. 2, 8
Classification by Timing
Akathisia can be classified based on when it appears during treatment:
- Acute akathisia: Occurs early in treatment
- Chronic akathisia: Persists beyond 3 months
- Tardive akathisia: Develops after prolonged exposure
- Withdrawal akathisia: Emerges when medications are reduced or stopped 6, 8
Assessment Tools
The Barnes Akathisia Rating Scale should be used to systematically evaluate and objectively track symptoms. 1, 2
Special Populations at Higher Risk
- Children and adolescents have higher risk for extrapyramidal side effects including akathisia compared to adults 7, 2
- Young age and male gender are additional risk factors 7
Critical Safety Concern with SSRIs
SSRI-induced akathisia is associated with increased suicidality, particularly with fluoxetine. 7, 2 Clinicians must systematically inquire about suicidal ideation before and after SSRI treatment initiation and be especially alert if akathisia develops. 7