ClinCalc Pro
Menu
Calculators Drugs Pathways AI Dx Donate Get the App
Sympathomimetic Vasopressor Pregnancy: Use with caution — safe for obstetric spinal hypotension but phenylephrine preferred

Ephedrine (IV — Anaesthesia)

Brand names: Ephedrine

Adult dose

Dose: 3–6 mg IV bolus; repeat as needed
Route: IV
Frequency: Bolus every 3–4 minutes as needed
Max: 30 mg total in a single episode
First-line vasopressor for spinal-induced hypotension (especially in obstetrics). Mixed alpha and beta agonist — increases BP and HR. Indirect acting — releases noradrenaline from nerve terminals. Less effective with repeated dosing (tachyphylaxis).

Paediatric dose

Dose: 0.1–0.2 mg/kg
Route: IV
Frequency: Bolus as needed
Max: Titrated to BP response
Paediatric vasopressor for spinal/epidural hypotension: 0.1–0.2 mg/kg IV bolus under specialist guidance.

Dose adjustments

Renal

No specific adjustment required.

Hepatic

No specific adjustment required.

Paediatric weight-based calculator

Paediatric vasopressor for spinal/epidural hypotension: 0.1–0.2 mg/kg IV bolus under specialist guidance.

Clinical pearls

  • In obstetric spinal anaesthesia: phenylephrine now preferred over ephedrine for maternal hypotension — less fetal acidosis (ephedrine crosses placenta and increases fetal metabolism)
  • Tachyphylaxis develops with repeated boluses — switch to phenylephrine or noradrenaline infusion if repeated doses needed
  • Unlike direct vasopressors (phenylephrine, noradrenaline), ephedrine increases both BP AND HR — useful if bradycardic hypotension

Contraindications

  • Hypertension
  • Tachycardia/tachyarrhythmias
  • Hyperthyroidism
  • MAOIs within 14 days (hypertensive crisis)

Side effects

  • Tachycardia
  • Hypertension
  • Arrhythmias
  • Fetal acidosis (obstetric use — compared to phenylephrine)
  • Tremor
  • Tachyphylaxis with repeated doses

Interactions

  • MAOIs (hypertensive crisis — contraindicated)
  • Oxytocin (hypertension if combined with vasopressors)
  • Halothane (sensitises myocardium to arrhythmias — avoid)

Monitoring

  • BP and HR after each bolus
  • Fetal HR in obstetric use (CTG)

Reference: BNFc; BNF 90; OAA (Obstetric Anaesthetists Association) Guidelines; NICE NG121 (Caesarean Section). Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

Calculators
Pathways