Physostigmine
Physostigmine is a cholinesterase inhibitor medication primarily used in ophthalmology for treating glaucoma and in emergency medicine for reversing anticholinergic toxicity. By inhibiting the enzyme acetylcholinesterase, it increases acetylcholine levels, restoring nerve function in conditions where cholinergic activity is deficient. It is one of the few cholinesterase inhibitors capable of crossing the blood-brain barrier.
Physostigmine is a cholinesterase inhibitor used primarily for glaucoma and to reverse anticholinergic toxicity by increasing acetylcholine levels in the nervous system.
Key facts at a glance
- ATC
- S01EB05
- RxNorm
- 8299
- Generic
- Physostigmine
- Class
- atc-s01
- Brands
- Anticholium
- Availability
- rx
- Lactation
- unknown
- Routes
- ophthalmic
- Forms
- injection, solution
- Regions
- US, EU, CN, JP
- Monitoring
- —
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Dosage and administration
- Usual dose
- 0.5-2 mg IV/IM
- Maximum
- consult physician
- Frequency
- every 5-30 minutes as needed
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 0.01-0.03 mg/kg IV/IM
- Maximum
- consult physician
- Frequency
- every 5-30 minutes as needed
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 0.5-1 mg IV/IM
- Maximum
- consult physician
- Frequency
- every 5-30 minutes as needed
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
Overdose information
Special Populations
10 groupspregnancy
first trimesteravoid if possible
avoid use during pregnancy unless benefits outweigh risks
regular fetal monitoring
Use of this medication in this population requires careful consideration of risks and benefits.
pregnancy
second trimesterreduce dose
use only if clearly needed with careful monitoring
fetal heart rate monitoring and uterine activity monitoring
Use with caution and monitor for adverse effects.
pregnancy
third trimesteravoid if possible
avoid use near term due to risk of premature labor
continuous fetal monitoring if use is necessary
Use of this medication in this population requires careful consideration of risks and benefits.
lactation
breastfeedingdiscontinue breastfeeding
do not use during breastfeeding due to potential excretion in milk
not applicable
Use of this medication in this population requires careful consideration of risks and benefits.
geriatric
elderlyreduce dose by 25-50%
use lower initial doses and monitor closely for adverse effects
close monitoring of vital signs and cardiac function
Use with caution and monitor for adverse effects.
pediatric_age
children under 12weight-based dosing with reduced dose
use only under close medical supervision with appropriate pediatric dosing
continuous cardiac monitoring and vital sign monitoring
Use with caution and monitor for adverse effects.
renal_impairment
mildno adjustment needed
monitor renal function during treatment
monitor renal function periodically
Use with caution and monitor for adverse effects.
renal_impairment
severereduce dose by 50%
use with extreme caution and extended dosing intervals
frequent plasma concentration monitoring if available
Use with caution and monitor for adverse effects.
hepatic_impairment
mildno adjustment needed
monitor liver function during treatment
periodic liver function tests
Use with caution and monitor for adverse effects.
hepatic_impairment
moderate to severereduce dose by 25-50%
use with extreme caution due to impaired metabolism
close monitoring of hepatic function and drug levels
Use with caution and monitor for adverse effects.
Statistics and clinical data
Drug class
Classification as reversible cholinesterase inhibitor
Mechanism of action
Primary pharmacodynamic mechanism
Common uses
Therapeutic applications
Commonly prescribed since
Historical prescribing information
Physostigmine is used to treat open-angle glaucoma and reverse toxic effects from anticholinergic or atropine overdoses. It may also be used in certain cases of amblyopia (lazy eye) and as an antidote for poisonous mushrooms containing muscarine.
It works by reversibly inhibiting acetylcholinesterase, the enzyme responsible for breaking down acetylcholine. This prevents the degradation of acetylcholine at nerve synapses, thereby increasing its concentration and enhancing cholinergic transmission throughout the nervous system.
Physostigmine is contraindicated in mechanical bowel or urinary obstruction and asthma. Due to its ability to cross the blood-brain barrier, it can cause CNS effects including seizures and confusion. It requires careful monitoring during administration, particularly in patients with cardiac disease, as it may cause bradycardia or arrhythmias.
Contraindications
Conditions and patient states where this medication should be avoided or used with caution.
Do not use (1)
Known allergy to this medication or its components
Use caution (1)
Consult healthcare provider for benefits vs risks assessment
Official drug label
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 24, 2026. · Read our editorial policy