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Acetylcholinesterase Inhibitor / Neuromuscular Blockade Reversal Pregnancy: Use during pregnancy or lactation has not been established; the possible hazards to mother and child must be weighed against the potential benefits in every case. Experience with myasthenia gravis has revealed no untoward effect of the drug on the course of pregnancy; as the severity of myasthenia gravis often fluctuates considerably, particular care is required to avoid cholinergic crisis due to overdosage. Only negligible amounts are excreted in breast milk, but attention should be paid to possible effects on the breast-feeding infant.

Neostigmine

Brand names: Neostigmine Methylsulfate

Neostigmine is an anticholinesterase used chiefly to reverse non-depolarising neuromuscular blockade at the end of anaesthesia, and also in conditions such as myasthenia gravis and post-operative ileus or urinary retention.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: REVERSAL OF NON-DEPOLARISING NEUROMUSCULAR BLOCKADE (adults): 2.5 mg by INTRAVENOUS injection over 1 minute, after or with glycopyrronium or atropine; repeat if necessary. MYASTHENIA GRAVIS (adults and children 12-17 years): 1-2.5 mg by SUBCUTANEOUS or INTRAMUSCULAR injection, repeated at suitable intervals throughout the day.
Route: Route differs by indication: INTRAVENOUS (given slowly, over 1 minute) for reversal of neuromuscular blockade; SUBCUTANEOUS or INTRAMUSCULAR for myasthenia gravis and for paralytic ileus / post-operative urinary retention.
Frequency: Reversal of neuromuscular blockade: single intravenous dose given over 1 minute, repeated if necessary. Myasthenia gravis: repeated at suitable intervals throughout the day.
Max: Reversal of non-depolarising neuromuscular blockade (intravenous): maximum 5 mg PER DOSE. Myasthenia gravis (subcutaneous/intramuscular): the SPC states a per-dose range of 1-2.5 mg and a usual TOTAL DAILY dose in adults of 5-20 mg - it does not state a single-dose maximum above 2.5 mg for this route, and the 5 mg intravenous ceiling must NOT be applied to subcutaneous or intramuscular myasthenia dosing.
Recommended doses are presented by indication and may be varied according to the individual needs of the patient. NEUROMUSCULAR BLOCKADE REVERSAL SAFETY: reversal should not be attempted unless there is spontaneous recovery from paralysis; atropine and neostigmine may be given simultaneously, but in patients with bradycardia the pulse rate should be increased to 80 per minute with atropine before administering neostigmine; a syringe of atropine sulfate should always be available to counteract severe cholinergic reactions. OTHER INDICATIONS: paralytic ileus and post-operative urinary retention - adults 0.5-2.5 mg by subcutaneous or intramuscular injection (children 0.125-1 mg); paroxysmal supraventricular tachycardia (intravenous) - treatment should be reserved for severe cases not responding to conventional treatment and under close supervision of a specialist experienced with its use, and NO dose is stated for this indication in the retrieved SPC. ELDERLY: no specific dosage recommendations, but these patients may be more susceptible to dysrhythmias. Neostigmine should not be given during cyclopropane or halothane anaesthesia, although it may be used after withdrawal of these agents. PAEDIATRIC MYASTHENIA GRAVIS (age-banded, not per-kg): children 1 month to 11 years, 200-500 micrograms repeated at suitable intervals throughout the day; children 12 to 17 years, as adults (1-2.5 mg); neonates up to 1 month, 150 micrograms/kg every 6-8 hours given 30 minutes before feeds, increased if necessary up to 300 micrograms/kg every 4 hours, with the daily dosage reduced until the drug can be withdrawn because of the self-limiting nature of the disease in neonates. The per-kg paediatric regimen in the paedDose field below is for NEUROMUSCULAR BLOCKADE REVERSAL only. Verify all paediatric dosing against a children's formulary. SOURCE: UK SPC for 'Neostigmine Methylsulfate Injection BP 2.5mg in 1ml'. US labelling (cross-check only, may differ from UK): reversal of non-depolarising blockade 0.03 mg/kg to 0.07 mg/kg by intravenous bolus, maximum total 0.07 mg/kg or 5 mg, whichever is less, with atropine (~15 micrograms/kg) or glycopyrrolate (~10 micrograms/kg) given before or concomitantly.

Paediatric dose

Dose: 50 micrograms/kg
Route: Intravenous injection over 1 minute, given after or with glycopyrronium or atropine
Frequency: Single dose, followed by a further dose of 25 micrograms/kg if required
Max: 2.5 mg per dose in children 1 month to 11 years and 12 to 17 years; no per-dose maximum is stated for neonates up to 1 month
THIS IS THE REVERSAL-OF-NON-DEPOLARISING-NEUROMUSCULAR-BLOCKADE DOSE ONLY. The UK SPC states the same 50 micrograms/kg (followed by a further 25 micrograms/kg if required) for neonates up to 1 month, children 1 month to 11 years, and children 12 to 17 years. Units are MICROGRAMS per kg, not milligrams. Different, non-per-kg paediatric doses apply in myasthenia gravis and in paralytic ileus / urinary retention - see adultDose.notes. Reversal should not be attempted unless there is spontaneous recovery from paralysis, and atropine/glycopyrronium must be given before or with neostigmine. Verify against a children's formulary before use.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Paediatric weight-based calculator

THIS IS THE REVERSAL-OF-NON-DEPOLARISING-NEUROMUSCULAR-BLOCKADE DOSE ONLY. The UK SPC states the same 50 micrograms/kg (followed by a further 25 micrograms/kg if required) for neonates up to 1 month, children 1 month to 11 years, and children 12 to 17 years. Units are MICROGRAMS per kg, not milligrams. Different, non-per-kg paediatric doses apply in myasthenia gravis and in paralytic ileus / urinary retention - see adultDose.notes. Reversal should not be attempted unless there is spontaneous recovery from paralysis, and atropine/glycopyrronium must be given before or with neostigmine. Verify against a children's formulary before use.

Verify in a children's formulary

Contraindications

  • Hypersensitivity to the active substance or to any of the excipients
  • Mechanical obstruction of the gastrointestinal or urinary tracts, peritonitis, or doubtful bowel viability
  • Should not be used in conjunction with depolarising muscle relaxants such as suxamethonium, as neuromuscular blockade may be potentiated

Side effects

  • Cardiac: bradycardia, decreased cardiac conduction, in severe cases possibly leading to heart block or cardiac arrest; hypotension
  • Gastrointestinal: nausea, vomiting, diarrhoea, abdominal cramps, salivary hypersecretion; increased intestinal motility may result in involuntary defecation
  • Respiratory: increased bronchial secretion, bronchospasm
  • Nervous system: cholinergic syndrome, especially at high doses (in patients with myasthenia gravis, cholinergic crisis may be difficult to distinguish from myasthenic crisis)
  • Immune: hypersensitivity, angioedema, anaphylactic reaction
  • Other: miosis, increased lacrimation, hyperhidrosis, muscle spasms, urinary incontinence

Interactions

  • Non-depolarising muscle relaxants (e.g. tubocurarine, gallamine, pancuronium) - neostigmine effectively antagonises their effect; this interaction is used therapeutically to reverse muscle relaxation after surgery
  • Depolarising muscle relaxants such as succinylcholine - neostigmine does not antagonise and may in fact prolong the phase I block
  • Atropine - antagonises the muscarinic effects of neostigmine; used to counteract the muscarinic symptoms of neostigmine toxicity
  • Aminoglycoside antibiotics and other drugs that interfere with neuromuscular transmission - should be used cautiously, if at all, in patients with myasthenia gravis, and the dose of neostigmine may have to be adjusted accordingly
  • Inhaled anaesthetics - neostigmine should not be given during cyclopropane or halothane anaesthesia, although it may be used after withdrawal of these agents (SPC section 4.4)

Clinical monograph

How it works

It reversibly inhibits acetylcholinesterase, increasing acetylcholine concentration at the neuromuscular junction and at muscarinic sites, thereby restoring transmission across the blocked junction.

Prescribing in practice

  • Its muscarinic effects (bradycardia, bronchoconstriction, increased secretions, salivation) require co-administration of an antimuscarinic such as glycopyrrolate or atropine.
  • It is ineffective and may be hazardous if given before some recovery of the block has occurred (it will not reverse a profound or deepening block).
  • It does not reverse depolarising (suxamethonium) blockade and may prolong it.

Monitoring

Monitor heart rate, neuromuscular recovery (train-of-four), and adequacy of ventilation during and after reversal.

Counselling the patient

  • This medicine is given by the anaesthetic team to help your muscles and breathing recover after surgery.
  • Increased saliva or a slow heartbeat can occur briefly and is managed by the team.

Evidence & guidelines

Use reflects established anaesthetic and neuromuscular practice; consult current prescribing references and the SPC.

Reference: AAGBI Guidelines; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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