What is the proper dosage and administration of hydrocortisone (corticosteroid) for an adult or pediatric patient experiencing an acute allergic reaction, considering factors such as severity, weight, and past medical history?

Hydrocortisone Preparation and Administration for Allergic Reactions

Administer hydrocortisone 200 mg IV (or IM if IV access unavailable) for adults and adolescents over 12 years experiencing acute allergic reactions, with age-adjusted dosing for children: 100 mg for ages 6-12 years, 50 mg for 6 months to 6 years, and 25 mg for infants under 6 months. 1, 2

Critical First-Line Treatment Priority

Epinephrine 0.3-0.5 mg intramuscularly (1:1000 dilution) into the anterolateral thigh must be administered immediately as the only first-line treatment for anaphylaxis—hydrocortisone is strictly adjunctive therapy and provides no acute benefit for airway edema or hypotension. 2, 3 Hydrocortisone should never delay or replace epinephrine administration. 3

Age-Specific Hydrocortisone Dosing

Adults and Adolescents (>12 years)

• 200 mg IV or IM 1, 2
• Administer slowly over 30 seconds to 10 minutes when given IV 4

Children (6-12 years)

• 100 mg IV or IM 1, 2

Young Children (6 months to 6 years)

• 50 mg IV or IM 1, 2, 5

Infants (<6 months)

• 25 mg IV or IM 1, 2

Preparation and Administration Technique

Reconstitution

• Add no more than 2 mL of Bacteriostatic Water for Injection or Bacteriostatic Sodium Chloride Injection to the 100 mg vial 4
• For IV infusion, after reconstitution, the solution may be added to 100-1000 mL of 5% dextrose in water or isotonic saline 4

Route Selection

• IV route is preferred when access is already established 3
• IM injection is acceptable when IV access is unavailable 1, 2
• Administer IV doses slowly over 30 seconds (for 100 mg) to 10 minutes (for 500 mg or more) 4

Complete Anaphylaxis Management Algorithm

Immediate Actions (First 5 Minutes)

1. Epinephrine 0.3-0.5 mg IM (anterolateral thigh) - repeat every 5-15 minutes if symptoms persist 1, 3
2. Position patient supine with legs elevated (unless respiratory distress present) 3
3. Provide supplemental oxygen and monitor oxygen saturation 3
4. Establish IV access and administer crystalloid fluid bolus (500-1000 mL for adults, 20 mL/kg for children) 3

Adjunctive Medications (After Epinephrine)

• Hydrocortisone at age-appropriate dose (see above) 1, 2
• H1-antihistamine: Diphenhydramine 25-50 mg IV/IM for adults (1-2 mg/kg for children) 3
• H2-antihistamine: Ranitidine 50 mg IV for adults (1 mg/kg for children) 3

Clinical Rationale and Timing

Hydrocortisone serves to prevent biphasic reactions (occurring in up to 20% of cases) and protracted anaphylaxis, but provides no immediate benefit during the acute phase. 2, 3 The anti-inflammatory effects take hours to manifest, which is why epinephrine remains the only medication that treats acute anaphylaxis. 3

Observation and Discharge Protocol

• Observe for minimum 4-6 hours after symptom resolution, with longer observation (up to 24 hours) for severe reactions, patients requiring multiple epinephrine doses, or those with persistent airway symptoms 1, 3

Discharge Medications

• Prednisone 1 mg/kg daily (maximum 60-80 mg) for 2-3 days 3
• H1-antihistamine (diphenhydramine) every 6 hours for 2-3 days 1
• H2-antihistamine (ranitidine) twice daily for 2-3 days 1
• Two epinephrine auto-injectors with hands-on training 3
• Written anaphylaxis action plan 3

Critical Pitfalls to Avoid

Common Errors

• Never rely on antihistamines or hydrocortisone alone for acute anaphylaxis—this significantly increases risk of progression to life-threatening reaction 1, 2
• Do not delay epinephrine administration to give hydrocortisone first 3
• Avoid premature discharge—biphasic reactions are unpredictable and can occur hours after initial symptom resolution 3

Rare but Important Consideration

• Hydrocortisone itself can rarely cause anaphylactic reactions 6, 7, 8
• If paradoxical worsening occurs immediately after hydrocortisone administration, consider hydrocortisone allergy and switch to methylprednisolone or dexamethasone 7, 9

Special Populations

Patients on Beta-Blockers

• If refractory to epinephrine after 2-3 doses and adequate fluid resuscitation, administer glucagon 1-5 mg IV over 5 minutes (20-30 mcg/kg for children, maximum 1 mg), followed by infusion at 5-15 mcg/min 3

Patients with Asthma History

• Consider higher corticosteroid doses and longer observation periods, as these patients are at higher risk for severe reactions 2, 3

Refractory Anaphylaxis

• Consider epinephrine IV infusion (5-15 mcg/min) for persistent hypotension despite IM epinephrine and fluids 3
• Prepare 50 mcg IV boluses (0.5 mL of 1:10,000 solution) for adults, titrating carefully with continuous cardiac monitoring 3