Redback Antivenom

Liverpool Hospital Emergency Department


  • Use is now regarded as controversial following the RAVE II trial where the benefits  were thought to be minimal relative to the risk of adverse effects
  • Use should be discussed with a Clinical Toxicologist
  • Generally considered when
    • There is persistent or intractable pain due to the bite despite aggressive  analgesic dosing including IV opiates
    • Considered in significant systemic features of latrodectism
      • (generalised pain  / autonomic features with severe sweating and haemodynamic lability)  


  • 500units of Red Back Spider antivenom each vial (contained in roughly 1-1.5mL)  

Dosage and Administration 

  • Dilute 2 vials (1000units) into 100mL of Sodium Chloride 0.9% and infuse over 20  minutes IV
    • (dose the same for adults and children) 
  • Antivenom should only be given in a resuscitation area with access to equipment  and adrenaline 

Side Effects 

  • Anaphylaxis 
  • If there is an acute allergic or anaphylactic reaction temporarily stop the  infusion and treat accordingly then recommence the infusion at a slower  rate.
  • Delayed serum sickness; fever, rash, arthralgia and myalgia 

Pit Falls: 

  • Provision of inadequate analgesic regime prior to use