Reviewed on 2/15/2022

What Is Neostigmine and How Does It Work?

Neostigmine is a prescription medicine used for the treatment of Myasthenia Gravis, Urinary Retention or Post-Op Distention, and for reversing the effects of Nondepolarizing Neuromuscular Blockade. 

What Are Dosages of Neostigmine?

Adult and pediatric dosage

Injectable solution (methylsulfate salt; Bloxiverz)

  • 0.5mg/mL
  • 1mg/mL

Tablet (bromide salt; Prostigmin)

  1. 15 mg

Myasthenia Gravis

Adult dosage

  • Acute: 0.5-2.5 mg IV/IM/SC once daily
  • Maintenance: 15-375 mg/day orally divided every 6 to 8 hours
  • Use injectable with 0.6-1.2 mg atropine IV to counteract muscarinic effects

Pediatric dosage

Use with atropine

  • 0.01-0.04 mg/kg IV/IM/SC every 2 to 3 hours or as needed
  • 2 mg/kg/day divided every 4 hours orally; no more than 375mg/day

Myasthenia Gravis Diagnosis

Adult dosage

  • 0.022 mg/kg IM x1 

Pediatric dosage

Use with atropine

  • 0.025-0.04 mg/kg IM x1 

Nondepolarizing Neuromuscular Blockade, Reversal

Adult and pediatric dosage

  • 0.03-0.07 mg/kg IV will generally achieve a TOF twitch ratio of 90% within 10-20 minutes of administration
  • Not to exceed 0.07 mg/kg or a cumulative total of 5 mg, whichever dose is less Inject by slow IV over at least 1 minute

Post-op Distention or Urinary Retention

Adult dosage

  • Prevention: 0.25mg IM after surgery. Repeat every 4 to 6 hours for 2-3 days
  • Treatment: 0.5-1 mg IM and up to every 3 hours or as needed (for 5 doses for retention)

Dosage Considerations – Should be Given as Follows: 

  • See “Dosages”

What Are Side Effects Associated with Using Neostigmine?

Common side effects of Neostigmine include:

  • nausea,
  • vomiting,
  • diarrhea,
  • abdominal cramps,
  • increased saliva and mucus,
  • decreased pupil size,
  • increased urination, and
  • increased sweating.

Serious side effects of Neostigmine include:

  • new or increased muscle cramps, weakness, or twitching,
  • new or increased difficulty swallowing,
  • slow, fast or irregular heartbeat,
  • dizziness,
  • shortness of breath,
  • headache,
  • seizures,
  • rash,
  • itching,
  • swelling of the face, tongue, or throat,
  • severe dizziness, and
  • trouble breathing.

Rare side effects of Neostigmine include:

  • none 

This is not a complete list of side effects and other serious side effects or health problems that may occur as a result of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

What Other Drugs Interact with Neostigmine?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

  • Neostigmine has severe interactions with no other drugs.
  • Neostigmine has serious interactions with the following drugs:
  • Neostigmine has moderate interactions with at least 65 other drugs.
  • Neostigmine has minor interactions with at least 22 other drugs. 

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions, concerns.

What Are Warnings and Precautions for Neostigmine?


  • Hypersensitivity, previous history of reaction to bromides
  • Peritonitis or mechanical GI or urinary tract obstruction

Effects of drug abuse

  • None

Short-Term Effects

  • See “What Are Side Effects Associated with Using Neostigmine?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Neostigmine?”


  • To lessen the risk of bradycardia, administer glycopyrrolate or atropine sulfate before therapy
  • Caution in epilepsy, bronchial asthma, bradycardia, recent coronary occlusion, vagotonia, hyperthyroidism, cardiac arrhythmias, peptic ulcer
  • In patients with certain cardiovascular conditions such as coronary artery disease, cardiac arrhythmias, or recent acute coronary syndrome, risk of blood pressure and heart rate complications may be increased; risk of these complications may also be increased in patients with myasthenia gravis; standard antagonism with anticholinergics (e.g., atropine) is generally successful to mitigate the risk of cardiovascular complications
  • Neonates; because of the self-limiting nature of myasthenia gravis, reduce daily dosage gradually released until the drug can be withdrawn
  • Avoid large doses in situations where there might be an increased absorption rate from the intestinal tract; caution when coadministered with anticholinergic drugs because of decreased GI motility
  • Differentiate between myasthenic crisis and cholinergic crisis caused by overdosage of neostigmine; both conditions result in extreme muscle weakness but require radically different treatment
  • Large doses administered when the neuromuscular blockade is minimal can produce neuromuscular dysfunction; the dose should be reduced if recovery from neuromuscular blockade is nearly complete
  • Anticholinesterase insensitivity can develop
  • If excess cholinergic symptoms develop, discontinue therapy
  • Atropine and epinephrine must be available to treat a hypersensitivity reaction
  • Not recommended for use in patients with vagotonia
  • May prolong the phase 1 block of depolarizing muscle relaxants

Pregnancy and Lactation

  • There are no adequate or well-controlled studies in pregnant women; not known whether neostigmine can cause fetal harm or affect reproductive capacity; should administer only if needed
  • Anticholinesterase drugs, including neostigmine, may cause uterine irritability and induce premature labor when administered to pregnant women near term
  • Lactation
    • The drug has not been studied in lactating women; not known whether neostigmine methylsulfate is present in human milk, or has effects on milk production or the breastfed child; the developmental and health benefits of breastfeeding should be considered along with the mother’s need for therapy and any potential adverse effects on breastfed child from the drug or the underlying maternal condition 
Medscape. Neostigmine.

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