Is dexamethasone (corticosteroid) indicated in the treatment of allergic reactions in adult patients?

Dexamethasone in Allergic Reactions

Yes, dexamethasone can be given in allergic reactions, but only as adjunctive therapy after epinephrine administration in severe reactions—it should never replace or delay epinephrine, which is the only first-line treatment for anaphylaxis. 1

Critical First-Line Treatment

• Epinephrine is the only first-line drug for anaphylaxis and must be administered immediately at 0.01 mg/kg intramuscularly in the anterolateral thigh 1
• Antihistamines and corticosteroids, including dexamethasone, should never be considered substitutes for epinephrine in anaphylaxis treatment 1
• Delayed use of epinephrine may be ineffective, and fatal outcomes are associated with delay or lack of epinephrine administration 1

When to Use Dexamethasone

Dexamethasone should be administered only after adequate epinephrine and fluid resuscitation in severe allergic reactions 1

Dosing for Acute Allergic Reactions

According to FDA labeling, for acute, self-limited allergic disorders or acute exacerbations of chronic allergic disorders 2:

• First day: 4-8 mg intramuscularly 2
• Subsequent days: Transition to oral therapy with tapering doses over 5-7 days 2

Adjunctive Therapy Algorithm

After epinephrine and initial stabilization 1:

1. Administer dexamethasone 4-8 mg IM/IV as adjunctive therapy 1
2. Add antihistamines and H2 blockers concurrently 1
3. Monitor for biphasic reactions for a minimum of 6 hours or until stable and symptoms regressing 1

Role in Milder Reactions

For milder forms of allergic reactions (flushing, urticaria, isolated mild angioedema) 3:

• H1 and H2 antihistamines are the primary treatment 3
• Corticosteroids are often recommended to prevent biphasic or protracted food-induced allergic reactions, though little data support their use 3
• Ongoing observation is warranted to ensure lack of progression to anaphylaxis 3
• If progression occurs, epinephrine should be administered immediately 3

Prevention of Biphasic Reactions

• Systemic corticosteroids are often recommended to prevent biphasic or protracted allergic reactions due to their anti-inflammatory properties 3
• After discharge, continuation of adjunctive treatment includes 3:
  • H1 antihistamine (diphenhydramine every 6 hours for 2-3 days) 3
  • H2 antihistamine (ranitidine twice daily for 2-3 days) 3
  • Corticosteroid (prednisone daily for 2-3 days) 3

Critical Pitfalls to Avoid

The most common reason for not using epinephrine is the use of antihistamines, which may place a patient at significantly increased risk for progression toward a life-threatening reaction 3

Important Caveats

• Corticosteroids are not routinely effective once hypersensitivity reactions occur, and premedication with oral corticosteroids is usually unsuccessful in preventing recurrent reactions 4
• Recent evidence from SHOT advises against using steroids and/or antihistamines indiscriminately, recommending a more personalized approach tailored to the patient's symptoms 3
• Repeated doses of steroids may further suppress immunity in immunocompromised patients 3

Rare but Important: Dexamethasone Allergy

While glucocorticoids are frequently used to treat allergic reactions, true allergic immediate-type reactions to glucocorticoids exist and can range from rash to anaphylaxis 5:

• A patient sensitized to one or a group of glucocorticoids does not have to refrain from all types 5
• Cross-reactions between different corticosteroids have been documented 6, 7
• If dexamethasone allergy is suspected, alternative glucocorticoids like methylprednisolone or deflazacort may be tolerated 5, 8