Should adrenaline (epinephrine) be administered during the early stages of an allergic reaction to intravenous (IV) antibiotics or only after anaphylaxis occurs?

Adrenaline Should Be Administered at the First Signs of Allergic Reaction to IV Antibiotics, Not Waiting for Full Anaphylaxis

Adrenaline (epinephrine) should be administered immediately when early signs of allergic reaction to IV antibiotics appear, without waiting for full anaphylaxis to develop. 1, 2 Early intervention with adrenaline can prevent progression to life-threatening anaphylaxis and significantly improve patient outcomes.

Recognition of Early Allergic Reactions

Early signs of allergic reactions to IV antibiotics that warrant immediate adrenaline administration include:

• Cutaneous signs (flushing, urticaria, angioedema)
• Early respiratory symptoms (throat tightness, hoarseness, mild wheezing)
• Early cardiovascular changes (tachycardia)
• Gastrointestinal symptoms (abdominal pain, nausea)

Rationale for Early Adrenaline Administration

• Allergic reactions to IV antibiotics can progress rapidly to life-threatening anaphylaxis within minutes 2
• Delayed administration of adrenaline has been implicated in contributing to fatalities 1
• The Anaesthesia guidelines explicitly state that "adrenaline should be given as early as possible" 1
• There is no absolute contraindication to epinephrine administration in anaphylaxis 1

Adrenaline Administration Protocol

Initial Dose:

• Adults: 0.3-0.5 mg (0.3-0.5 mL of 1:1000 solution) intramuscularly 1, 3
• Children >30 kg: 0.3-0.5 mg IM
• Children <30 kg: 0.01 mg/kg IM, up to 0.3 mg 3

Administration Site:

• Inject into anterolateral aspect of the mid-thigh (vastus lateralis) for optimal absorption 1, 3

Repeat Dosing:

• May repeat every 5-10 minutes if symptoms persist or worsen 3
• The 5-minute interval between injections can be shortened if clinically necessary 1

Concurrent Management Steps

1. Stop the IV antibiotic infusion immediately
2. Call for help (resuscitation team in hospital, emergency services in community)
3. Position patient appropriately (supine with legs elevated if hypotensive)
4. Administer oxygen if needed
5. Establish IV access if not already present
6. Begin fluid resuscitation with crystalloids (500 mL-1 L rapid bolus for adults) 1

Secondary Management

After initial adrenaline and fluid resuscitation:

• Administer chlorphenamine 10 mg IV (adult dose) 1
• Administer hydrocortisone 200 mg IV (adult dose) 1
• For persistent bronchospasm: consider inhaled bronchodilators or IV salbutamol 1
• For persistent hypotension: consider adrenaline infusion (0.05-0.1 μg/kg/min) 1, 2

Common Pitfalls to Avoid

• Delayed adrenaline administration: Waiting for full anaphylaxis to develop before giving adrenaline increases mortality risk 1
• Overreliance on antihistamines and corticosteroids: These are second-line treatments and should never replace adrenaline 2
• Inadequate fluid resuscitation: Essential to combat vasodilatation and capillary leakage 1
• Subcutaneous instead of intramuscular injection: IM administration provides faster and more reliable absorption 1

Monitoring and Follow-up

• Observe patient in a monitored area for minimum 6 hours or until stable 1
• Consider obtaining mast cell tryptase levels (at 1-2 hours after reaction onset and again at 24 hours) 1
• Document the reaction in detail and ensure appropriate allergy documentation

Early administration of adrenaline at the first signs of allergic reaction to IV antibiotics is the cornerstone of effective management and can be lifesaving. The benefits of early adrenaline treatment far outweigh the risks of unnecessary dosing 1.