This handout is for acute drug-induced dystonia & extrapyramidal syndromes — acute dystonia (oculogyric crisis / torticollis / trismus / opisthotonos / laryngeal dystonia = airway emergency) vs acute akathisia vs drug-induced parkinsonism after dopamine-antagonist exposure; iv/im anticholinergic (benztropine 1-2 mg or diphenhydramine 25-50 mg) reversal + airway management if laryngeal + offending-agent management + propranolol-first-line akathisia + parkinsonism dose-reduction; rule out nms / serotonin syndrome (pierre drug saf 2005 pmid 16180939; van harten bmj 1999 pmid 10463905). Your care team identified this based on: acute sustained involuntary posturing — oculogyric crisis, torticollis/retrocollis, trismus, buccolingual crisis, opisthotonos — within hours-to-days of a dopamine-antagonist (antipsychotic / metoclopramide / prochlorperazine / promethazine / droperidol); first-exposure or dose-escalation (van harten bmj 1999 pmid 10463905; pierre drug saf 2005 pmid 16180939).
Other reasons your team may use this plan: stridor / dysphonia / dyspnea / sense of throat tightening after a dopamine-antagonist — laryngeal dystonia: airway emergency requiring immediate iv anticholinergic + airway management (van harten bmj 1999 pmid 10463905; pierre drug saf 2005 pmid 16180939); subjective inner restlessness + objective pacing / leg-crossing-uncrossing / inability to sit still after starting/escalating an antipsychotic or antiemetic — acute akathisia (suicidality + aggression association — re-screen) (barnes br j psychiatry 1989 pmid 2574607; drotts ann emerg med 1999 pmid 10499951); bradykinesia + cogwheel rigidity + (often symmetric) resting/postural tremor + hypomimia emerging over days-weeks of a dopamine-antagonist — drug-induced parkinsonism (elderly predominant) (seitz drugs aging 2009; pierre drug saf 2005 pmid 16180939).
Take these medications exactly as prescribed. Do not stop or change a dose without talking to your provider.
| Medication | Starting dose | How | When | What it does |
|---|---|---|---|---|
| benztropine | 1-2 mg IV (preferred for speed in laryngeal/severe) or IM (pediatric / elderly dose-reduced 0.5-1 mg) | IV/IM | once; may repeat after 20-30 min if no response (max ~6 mg/24 h acute) | van Harten BMJ 1999 PMID 10463905 — IV/IM anticholinergic is first-line and usually produces dramatic reversal within minutes (a diagnostic-therapeutic trial); benztropine preferred where less sedation desired; IV route for laryngeal/severe; dose-reduce + minimise in elderly (delirium, urinary retention, falls — AGS Beers 2023) |
| diphenhydramine | 25-50 mg IV/IM (pediatric 1 mg/kg IV/IM, max 50 mg; elderly minimise) | IV/IM | once; may repeat after 20-30 min if no response | van Harten BMJ 1999 PMID 10463905; Lima Cochrane PMID 15106194 — diphenhydramine IV/IM equally effective first-line anticholinergic for acute dystonia; added sedation can be useful; weight-based in pediatrics (highest-risk group); minimise in elderly + delirium (anticholinergic — AGS Beers 2023) |
| lorazepam | 1-2 mg IV/IM (elderly 0.5-1 mg) | IV/IM | once; titrate q15-30 min PRN for refractory/recurrent dystonia | Pierre Drug Saf 2005 PMID 16180939 — benzodiazepine adjunct for acute dystonia not fully responsive to anticholinergic, or severe generalized/laryngeal cases; muscle relaxation + anxiolysis; not a substitute for anticholinergic |
| airway management + escalation (laryngeal dystonia) | For LARYNGEAL dystonia (stridor / dysphonia / dyspnea): immediate IV benztropine/diphenhydramine + high-flow O2 + airway equipment at bedside + senior/anesthesia/ENT alert; prepare for definitive airway if obstruction progresses despite reversal | NA | immediate, continuous until reversed | van Harten BMJ 1999 PMID 10463905 — laryngeal dystonia is a life-threatening airway emergency; IV anticholinergic usually reverses rapidly but airway readiness + escalation must not be deferred while waiting for response |
Plan: Acute dystonia reversal — IV/IM anticholinergic (benztropine or diphenhydramine), repeat if needed, benzodiazepine adjunct for refractory; AIRWAY MANAGEMENT + escalate if LARYNGEAL dystonia (van Harten BMJ 1999 PMID 10463905; Pierre Drug Saf 2005 PMID 16180939; Lima Cochrane anticholinergics for acute dystonia PMID 15106194)
Call 911 or go to the nearest emergency room right away if you have:
Document the offending agent as an adverse drug reaction / allergy-list entry; communicate the EPS-risk to prescribers; choose a lower-EPS-risk agent for ongoing psychiatric need (route disease-specific engine); akathisia → psychiatric follow-up + adherence support; parkinsonism → confirm resolution off agent vs unmasked idiopathic PD (neurology); patient education on early dystonia recognition + return precautions (Pierre Drug Saf 2005 PMID 16180939; Seitz Drugs Aging 2009)
Guideline: Acute drug-induced extrapyramidal syndromes — Pierre JM Drug Saf 2005 PMID 16180939 (extrapyramidal side effects of antipsychotics: recognition + acute management) + van Harten PN BMJ 1999 PMID 10463905 (acute dystonia clinical review + anticholinergic reversal) + Cochrane systematic reviews (Lima — anticholinergics for acute dystonia PMID 15106194; propranolol/beta-blockers for acute akathisia PMID 15495018; benzodiazepines for acute akathisia PMID 11034738) + Poyurovsky Br J Psychiatry 2001 PMID 11581110 (mirtazapine for akathisia) + Barnes Br J Psychiatry 1989 PMID 2574607 (Barnes Akathisia Rating Scale) + ED-antiemetic-EPS evidence (Drotts Ann Emerg Med 1999 PMID 10499951; Vinson Ann Emerg Med 2001 PMID 11574794) + Caroff J Clin Psychiatry 2002 PMID 12562137 (movement-disorder spectrum) — explicitly distinguished from NMS (Strawn AJP 2007 PMID 17541055) and serotonin syndrome (Boyer NEJM 2005 PMID 15784664)