What is the recommended hydrocortisone (cortisol) dosing for an acute allergic reaction in an individual with a known fish allergy?

Hydrocortisone Dosing for Acute Allergic Reactions to Fish

For acute allergic reactions to fish, hydrocortisone 100 mg IV should be administered as adjunctive therapy only after epinephrine has been given first, with the understanding that corticosteroids provide no acute benefit but may help prevent biphasic reactions. 1

Critical First-Line Treatment

Epinephrine is the only first-line treatment for acute allergic reactions to fish and must never be delayed or replaced by corticosteroids. 1

• Administer epinephrine 0.3-0.5 mg intramuscularly (1:1000 dilution) into the anterolateral thigh immediately for any signs of anaphylaxis 2, 1
• Repeat epinephrine every 5-15 minutes as needed if symptoms persist or progress 2, 1
• Position the patient supine with legs elevated unless respiratory distress is present 1
• Establish IV access and administer crystalloid fluid bolus (500-1000 mL for adults, 20 mL/kg for children) 1

Hydrocortisone Dosing Regimens

Adult Dosing

• Hydrocortisone 100 mg IV is the standard dose for acute allergic reactions 2, 1
• Alternative: Methylprednisolone 1-2 mg/kg IV (typically 40-80 mg for a 70 kg adult) 1
• For severe reactions requiring prolonged treatment, hydrocortisone 100 mg IV every 6 hours may be continued for 24-48 hours 2
• The FDA label indicates that initial doses of 100-500 mg may be used depending on severity, with repeat dosing at 2,4, or 6-hour intervals as needed 3

Pediatric Dosing

• Children aged 6-12 years: Hydrocortisone 100 mg IM or IV 1
• Children aged 6 months to 6 years: Hydrocortisone 50 mg IM or IV 1
• Children under 6 months: Hydrocortisone 25 mg IM or IV 1
• Alternative calculation: 0.56 to 8 mg/kg/day in divided doses (20-240 mg/m² body surface area/day) 3

Complete Management Algorithm

Step 1: Immediate Treatment (First 5 Minutes)

• Administer epinephrine 0.3-0.5 mg IM immediately 2, 1
• Position patient supine with legs elevated 1
• Establish IV access and begin fluid resuscitation 1
• Administer supplemental oxygen and monitor oxygen saturation 1

Step 2: Adjunctive Medications (After Epinephrine)

• Hydrocortisone 100 mg IV or methylprednisolone 1-2 mg/kg IV 2, 1
• H1-antihistamine: Diphenhydramine 25-50 mg IV (1-2 mg/kg in children) 2, 1
• H2-antihistamine: Ranitidine 50 mg IV or famotidine 20 mg IV 2, 1

Step 3: For Persistent Symptoms

• Repeat epinephrine 0.3-0.5 mg IM every 5-15 minutes as needed 2, 1
• For persistent bronchospasm: Albuterol 2.5-5 mg via nebulizer 2, 1
• For refractory hypotension: Consider epinephrine IV infusion (5-15 mcg/min) 1

Role and Limitations of Corticosteroids

Corticosteroids have a delayed onset of action (4-6 hours) and provide no benefit in treating acute anaphylaxis symptoms. 2

• Corticosteroids are given to potentially prevent biphasic reactions, which occur in up to 20% of cases within 3 days 2
• The evidence supporting corticosteroids for preventing biphasic reactions is limited and not definitive 2, 1
• Corticosteroids should be considered particularly for patients with: 1
  • History of asthma
  • Severe or prolonged anaphylaxis requiring multiple epinephrine doses
  • Significant generalized urticaria or angioedema

Observation and Discharge Protocol

• Observe patients for a minimum of 4-6 hours after symptom resolution 1, 4
• Extend observation for patients with severe reactions, persistent airway symptoms, or those requiring multiple epinephrine doses 1
• All biphasic reactions reported to date have occurred within 3 days, so treatment should be stopped within 2-3 days 2

Discharge Medications

• Prednisone 1 mg/kg daily (maximum 60-80 mg) for 2-3 days 1
• H1-antihistamine for 2-3 days 1
• H2-antihistamine twice daily for 2-3 days 1
• Two epinephrine auto-injectors with hands-on training 1, 4

Special Populations

Patients on Beta-Blockers

• If hypotension persists despite epinephrine and fluid resuscitation, administer glucagon 1-5 mg IV over 5 minutes 2, 1
• Follow with continuous infusion at 5-15 mcg/min 2, 1
• Pediatric dose: 20-30 mcg/kg (maximum 1 mg) IV over 5 minutes 2, 1

Critical Pitfalls to Avoid

• Never delay or withhold epinephrine while administering corticosteroids - antihistamines and corticosteroids do not substitute for epinephrine 1, 4
• Do not rely on corticosteroids alone for acute symptom management 2, 1
• Do not discharge patients prematurely, especially those with airway involvement 1
• Do not prescribe corticosteroids without also providing epinephrine auto-injectors 1

Context Regarding Fish Allergy

There is no evidence that seafood or fish allergies require different corticosteroid dosing than other food allergies. 2

• The misconception that fish allergies are related to iodine or contrast media reactions is false 2
• Fish allergy is IgE-mediated and can cause severe, life-threatening anaphylaxis 5, 6, 7
• Fish allergy is typically lifelong and children usually do not outgrow it 6, 7
• Reactions can occur from ingestion, inhalation of cooking vapors, or contact with fish 6, 7