Do we need to administer adrenaline (epinephrine) when allergic symptoms due to intravenous (IV) antibiotics are present, in anticipation of anaphylaxis?

Management of Allergic Reactions to IV Antibiotics: When to Administer Adrenaline

Adrenaline should be administered as early as possible when allergic symptoms due to IV antibiotics appear, without waiting for full anaphylaxis to develop, as there is consensus that early intervention reduces morbidity and mortality. 1

Assessment of Allergic Reactions

Allergic reactions to IV antibiotics can range from mild symptoms to life-threatening anaphylaxis. The severity classification helps determine appropriate management:

Grade I (Mild)

• Cutaneous signs only (erythema, urticaria, angioedema)

Grade II (Moderate)

• Cutaneous signs plus:
• Hypotension (not life-threatening)
• Mild bronchospasm

Grade III (Life-threatening)

• Severe hypotension
• Severe bronchospasm
• Life-threatening arrhythmias

Grade IV (Cardiac arrest)

• Cardiac or respiratory arrest

Management Algorithm

For Any Allergic Symptoms (Even Mild)

1. Stop administration of the suspected antibiotic immediately
2. Maintain airway, breathing, and circulation (ABC approach) 1
3. For Grade I reactions:
   • Close monitoring for progression
   • Consider antihistamines after ensuring stability

For Grade II Reactions

1. Administer IV adrenaline 20-50 μg (0.2-0.5 mL of 1:10,000 solution) 1
2. Administer crystalloid 500 mL as rapid bolus 1
3. If IV access is not available, give IM adrenaline 300 μg (0.3 mL of 1:1000 solution) 1
4. Repeat adrenaline dose after 2 minutes if unresponsive to initial dose 1

For Grade III Reactions

1. Administer IV adrenaline 50-100 μg (0.5-1 mL of 1:10,000 solution) 1
2. Administer crystalloid 1 L as rapid bolus 1
3. Increase adrenaline to 200 μg at 2 minutes if unresponsive to initial dose 1

For Grade IV Reactions

1. Follow advanced life support guidelines including IV adrenaline 1 mg 1
2. Initiate cardiac compressions 1

Secondary Management (After Initial Stabilization)

1. Administer chlorphenamine 10 mg IV (adult dose) 1
2. Administer hydrocortisone 200 mg IV (adult dose) 1
3. Consider alternative vasopressors if blood pressure does not recover despite adrenaline 1
4. Treat persistent bronchospasm with inhaled or IV bronchodilators 1

Important Considerations

Why Early Adrenaline is Critical

• Allergic reactions to IV antibiotics can progress rapidly to life-threatening anaphylaxis 1
• Delayed administration of adrenaline is associated with increased mortality 2
• Clinical features can appear within minutes but may be delayed by up to an hour with antibiotics 1

Common Pitfalls to Avoid

1. Delaying adrenaline administration - This is the most common error in managing allergic reactions 3
2. Using incorrect routes or doses - Only 14.4% of hospital doctors administer adrenaline correctly in anaphylaxis 3
3. Relying solely on antihistamines - These are second-line therapies and should never be used alone 1
4. Underestimating mild symptoms - Allergic reactions can progress rapidly 1, 2

Safety of Adrenaline

• Side effects occur in only about 21.6% of cases and are usually mild (tremors, palpitations, anxiety) 4
• Potentially severe adverse effects (high blood pressure, chest discomfort, ECG alterations) occur in only 3% of cases 4
• The risk of withholding adrenaline far outweighs the risk of administering it 4, 5

Monitoring After Treatment

• Observe patient in a monitored area for a minimum of 6 hours or until stable 1
• Take blood samples for Mast Cell Tryptase at 1 hour, 2-4 hours, and 24+ hours after reaction 1

Pediatric Dosing

For children, adrenaline dosing is weight-based:

• 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

The evidence clearly supports early intervention with adrenaline when allergic symptoms to IV antibiotics appear, rather than waiting for full anaphylaxis to develop. This approach minimizes the risk of progression to life-threatening anaphylaxis and improves patient outcomes.