Patient handout

Anticholinergic toxidrome

PRODUCTION

1. Your condition

This handout is for anticholinergic toxidrome. Your care team identified this based on: agitated/hyperactive delirium (mumbling, picking at air, hallucinations) + dry flushed skin [acmt physostigmine guidance 2018].

Other reasons your team may use this plan: reported ingestion of diphenhydramine / tca / antipsychotic / atropine / scopolamine / dicyclomine / oxybutynin / cyclobenzaprine [2024 crit-care tox review]; jimsonweed / datura / belladonna plant or seed-tea exposure (prolonged course) [2025 crit-care tox review]; sinus tachycardia + dilated pupils + anhidrotic hyperthermia cluster [burns 2000].

2. Your medications

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
lorazepam	2 mg IV, repeat/titrate q5–10 min to calm-but-rousable	IV	titrated PRN	First-line: controls agitation/seizure, reduces heat generation and rhabdo risk; titratable; preferred over antipsychotics which worsen antimuscarinic burden, QT and thermoregulation [Burns 2000]
diazepam	5–10 mg IV, repeat q5–10 min	IV	titrated PRN	Rapid-onset alternative for seizure/severe agitation [2024 crit-care tox review]
midazolam	0.05–0.1 mg/kg IV bolus, then infusion if continuous sedation needed	IV	bolus then infusion	Infusion option for refractory agitation requiring deep continuous sedation in ICU

Plan: Anticholinergic — benzodiazepine sedation → active cooling → physostigmine (pure antimuscarinic, ECG-gated) → sodium bicarbonate if QRS wide → supportive (2024 crit-care tox review; ACMT physostigmine guidance 2018)

4. When to seek emergency care

Call 911 or go to the nearest emergency room right away if you have:

Core temperature >39°C with anhidrotic skin in an antimuscarinic toxidrome [Burns 2000](life-threatening)
QRS >100 ms, terminal R in aVR, or known TCA/diphenhydramine co-ingestion (Na-channel blockade) [2024 crit-care tox review](life-threatening)
Seizure (single or status) in antimuscarinic toxicity — diphenhydramine notably proconvulsant [2024 crit-care tox review](life-threatening)
Severe agitation/combativeness with rising CK or hyperthermia (rhabdomyolysis risk) [Burns 2000]
Refractory pure antimuscarinic delirium (central + peripheral signs) with NORMAL QRS and no TCA/Na-channel co-tox, no asthma, no obstruction, no AV block [ACMT physostigmine guidance 2018]
Confirmed/suspected Datura, jimsonweed, or belladonna exposure — delayed onset and days-long delirium [2025 crit-care tox review]

5. Follow-up

Psychiatry safety plan if intentional; medication reconciliation / deprescribe anticholinergic burden (geriatric); poison-prevention + plant-identification education; renal follow-up if rhabdo-AKI; counsel that Datura/jimsonweed delirium can persist days [2025 crit-care tox review]

6. Sources

Guideline: 2024-2025 critical-care toxicology reviews; ACMT physostigmine guidance; Burns 2000 physostigmine-vs-benzodiazepine for anticholinergic poisoning