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Neostigmine: Side Effects

When neostigmine is administered to reverse neuromuscular blockade (NMB), the nicotinic effects are desired but muscarinic effects can be problematic.


  • Muscarinic effect results in bradycardia by slowed conduction through atrioventricular (AV) node
  • Must be dosed in combination with glycopyrrolate, which is vagolytic and has a similar onset of effect
  • Hypotension secondary to decreased in peripheral vascular resistance

Nausea and Vomiting

  • Conflicting studies with some reporting increased postoperative nausea and vomiting (PONV), some with antiemetic effect, and others showing no difference.
  • Meta-analysis by Tramer and Fuchs-Bader of 1,100 patients showed incidence of vomiting in 17-33% and dose-dependent relationship between neostigmine and PONV.


  • Bronchospasm due to cholinergic effect
  • Hypoxia and increased secretions


  • Miosis, increased gastrointestinal secretions and motility, possible NMB at high doses

Side effects must be carefully balanced against the potential for residual weakness if patient does not have neuromuscular blockade antagonized.