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Physostigmine Dosage

Medically reviewed by Last updated on Mar 31, 2022.

Applies to the following strengths: 1 mg/mL

Usual Adult Dose for Anticholinergic Syndrome

Post anesthesia care:

Initial dose: 0.5 to 1 mg, IM or slow IV, at no more than 1 mg/minute
-May repeat dose at 10 to 30 minute intervals if desired response is not obtained

Overdose of drugs that cause anticholinergic syndrome:

2 mg, IM or slow IV, at no more than 1 mg/minute
-May repeat dose if life threatening signs (e.g. arrhythmia, convulsions, coma) occur

Usual Pediatric Dose for Anticholinergic Syndrome

0.02 mg/kg, IM or slow IV, at no more than 0.5 mg/minute
-May repeat dose at 5 to 10 minute intervals if toxic effects persist (and no cholinergic effects) until a therapeutic effect is obtained.
Maximum dose: 2 mg

Renal Dose Adjustments

Data not available

Liver Dose Adjustments

Data not available

Dose Adjustments

-Discontinue for excessive salivation, emesis, urination, or defecation.
-Reduce dosage for excessive sweating or nausea.


Atropine is an antidote for physostigmine. Because of the possibility of hypersensitivity in an occasional patient, atropine sulfate injection should always be at hand when physostigmine is administered.


Data not available

Other Comments

Administration advice:
-Rapid administration can cause bradycardia, hypersalivation leading to respiratory difficulties, and convulsions.

Storage requirements:
-Store at controlled room temperature.
-Protect from light.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.