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

Adrenaline (Epinephrine) Should Be Given at the Early Stage of Allergic Reactions to IV Antibiotics

Adrenaline should be administered immediately when early signs of allergic reactions to IV antibiotics appear, without waiting for full anaphylaxis to develop, as early intervention prevents progression to life-threatening anaphylaxis and improves outcomes. 1

Understanding Allergic Reactions to IV Antibiotics

Allergic reactions to IV antibiotics can progress rapidly, often within minutes, from mild symptoms to life-threatening anaphylaxis. These reactions can be classified into four grades:

• Grade I: Cutaneous signs only (rash, urticaria)
• Grade II: Moderate multi-organ involvement
• Grade III: Life-threatening hypotension or bronchospasm
• Grade IV: Cardiac or respiratory arrest

Immediate Management Protocol

Step 1: Recognition and Initial Actions

• Stop the IV antibiotic administration immediately
• Call for help and note the time
• Maintain airway and administer 100% oxygen
• Position patient appropriately (supine with legs elevated if hypotensive) 2

Step 2: Administer Adrenaline

• For early allergic reactions (even Grade I that are persistent or progressing):

  • Administer adrenaline 0.5 mg (0.5 mL of 1:1000 solution) intramuscularly in adults 2
  • Inject into the anterolateral thigh for optimal absorption 3
  • May repeat every 5-10 minutes as necessary if symptoms persist 3

• For children:

  • 12 years: 500 μg IM (0.5 mL of 1:1000 solution)

  • 6-12 years: 300 μg IM (0.3 mL of 1:1000 solution)
  • <6 years: 150 μg IM (0.15 mL of 1:1000 solution) 1

Step 3: Fluid Resuscitation

• Administer crystalloid 500 mL as rapid bolus in adults for Grade II reactions or higher 2
• For severe reactions (Grade III/IV), administer 1L crystalloid rapidly 2

Step 4: Secondary Management

• Administer chlorphenamine 10 mg IV (adult dose) 2
• Administer hydrocortisone 200 mg IV (adult dose) 2
• Consider inhaled or IV bronchodilators for persistent bronchospasm 2

Special Considerations

Intravenous Adrenaline

• For severe reactions with hypotension not responding to IM adrenaline:
  • Consider IV adrenaline 50 μg (0.5 mL of 1:10,000 solution) 2
  • For persistent hypotension, consider adrenaline infusion (0.05-0.1 μg/kg/min) 2
  • Note: IV adrenaline should only be administered by experienced clinicians with appropriate monitoring

Monitoring and Follow-up

• Monitor vital signs continuously
• Observe for at least 6 hours after treatment, as biphasic reactions can occur 2
• Obtain mast cell tryptase levels (ideally at 1-2 hours after reaction onset and again at 24 hours) 2

Common Pitfalls to Avoid

1. Delaying adrenaline administration - This is the most critical error. Delayed administration of adrenaline has been implicated in fatalities 2

2. Overreliance on antihistamines and corticosteroids - These are second-line treatments and should never be used alone in place of adrenaline 2

3. Inadequate fluid resuscitation - Essential to combat vasodilatation in moderate to severe reactions 2

4. Inappropriate route of administration - Intramuscular injection into the thigh is superior to subcutaneous injection for rapid absorption 3, 4

Evidence-Based Rationale

The Association of Anaesthetists of Great Britain and Ireland (AAGBI) guidelines emphasize that "adrenaline should be given as early as possible" in suspected allergic reactions 2. This recommendation is supported by multiple studies showing that delayed administration of epinephrine contributes to anaphylaxis fatalities 2.

The British Journal of Anaesthesia guidelines similarly recommend early intervention with adrenaline for suspected allergic reactions, noting that "epinephrine is the first-line treatment in all cases of anaphylaxis" 2.

Early administration of adrenaline is critical because it addresses multiple pathophysiological aspects of allergic reactions simultaneously: it reverses peripheral vasodilation, reduces mucosal edema, increases cardiac contractility, and inhibits further mediator release from mast cells and basophils 4, 5.

Remember: There is no absolute contraindication to epinephrine administration in anaphylaxis or severe allergic reactions 2. The benefits of early intervention far outweigh the risks of adverse effects in the context of a potentially life-threatening reaction.