Acute allergic reaction: Difference between revisions
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#[[H1 antagonist]]: [[Diphenhydramine]] 50mg IV/IM/PO | #[[H1 antagonist]]: [[Diphenhydramine]] 50mg IV/IM/PO | ||
#*H1 antagonists with low sedating activity, such as fexofenadine, loratadine, cetirizine, are preferred over [[diphenhydramine]] and hydroxyzine when appropriate<ref>[Guideline] Zuberbier T, Asero R, Bindslev-Jensen C, Walter Canonica G, Church MK, Giménez-Arnau AM, et al. EAACI/GA(2)LEN/EDF/WAO guideline: management of urticaria. Allergy. 2009 Oct. 64(10):1427-43</ref> | #*H1 antagonists with low sedating activity, such as fexofenadine, loratadine, cetirizine, are preferred over [[diphenhydramine]] and hydroxyzine when appropriate<ref>[Guideline] Zuberbier T, Asero R, Bindslev-Jensen C, Walter Canonica G, Church MK, Giménez-Arnau AM, et al. EAACI/GA(2)LEN/EDF/WAO guideline: management of urticaria. Allergy. 2009 Oct. 64(10):1427-43</ref> | ||
#**[[Cetirizine]] 10mg IV/PO (6-11 years old: 5-10 mg IV; 6 mo - 5 years: 2.5 mg IV) | |||
#[[H2 antagonist]]: [[Famotidine]] 40mg '''OR''' [[ranitidine]] 150mg IV/IM/PO | #[[H2 antagonist]]: [[Famotidine]] 40mg '''OR''' [[ranitidine]] 150mg IV/IM/PO | ||
#*Improves urticaria but not angioedema at 2 hours<ref>Lin, RY et al. Improved Outcomes in Patients With Acute Allergic Syndromes Who Are Treated With Combined H1 and H2 Antagonists. Annals of Emergency Medicine. 36:5 NOVEMBER 2000.</ref> | #*Improves urticaria but not angioedema at 2 hours<ref>Lin, RY et al. Improved Outcomes in Patients With Acute Allergic Syndromes Who Are Treated With Combined H1 and H2 Antagonists. Annals of Emergency Medicine. 36:5 NOVEMBER 2000.</ref> | ||
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==Disposition== | ==Disposition== | ||
*Consider brief observation in the ED for improvement of symptoms | *Consider brief observation in the ED for improvement of symptoms | ||
*Send home with an [[anaphylaxis]] emergency plan and [[epinephrine]] autoinjector! (Epi-Pen) | |||
==See Also== | ==See Also== | ||
Latest revision as of 21:47, 29 January 2025
Background
- Similar to Anaphylaxis but does not meet all the requirements (i.e. just skin manifestations)
- Type I hypersensitivity reaction
Clinical Features
- Presentation can be delayed
Differential Diagnosis
Acute allergic reaction
- Allergic reaction/urticaria
- Anaphylaxis
- Angioedema
- Anxiety attack
- Asthma exacerbation
- Carcinoid syndrome
- Cold urticaria
- Contrast induced allergic reaction
- Scombroid
- Shock
- Transfusion reaction
Evaluation
- Clinical
- Rule out Anaphylaxis
- Difficult to differentiate from Angioedema
Management
- H1 antagonist: Diphenhydramine 50mg IV/IM/PO
- H1 antagonists with low sedating activity, such as fexofenadine, loratadine, cetirizine, are preferred over diphenhydramine and hydroxyzine when appropriate[1]
- Cetirizine 10mg IV/PO (6-11 years old: 5-10 mg IV; 6 mo - 5 years: 2.5 mg IV)
- H1 antagonists with low sedating activity, such as fexofenadine, loratadine, cetirizine, are preferred over diphenhydramine and hydroxyzine when appropriate[1]
- H2 antagonist: Famotidine 40mg OR ranitidine 150mg IV/IM/PO
- Improves urticaria but not angioedema at 2 hours[2]
- Consider corticosteroid: methylprednisolone 125mg IV/IM OR prednisone 60mg PO
- Continue steroid burst if outpatient (40mg prednisone PO x 5 days)
Disposition
- Consider brief observation in the ED for improvement of symptoms
- Send home with an anaphylaxis emergency plan and epinephrine autoinjector! (Epi-Pen)
See Also
References
- ↑ [Guideline] Zuberbier T, Asero R, Bindslev-Jensen C, Walter Canonica G, Church MK, Giménez-Arnau AM, et al. EAACI/GA(2)LEN/EDF/WAO guideline: management of urticaria. Allergy. 2009 Oct. 64(10):1427-43
- ↑ Lin, RY et al. Improved Outcomes in Patients With Acute Allergic Syndromes Who Are Treated With Combined H1 and H2 Antagonists. Annals of Emergency Medicine. 36:5 NOVEMBER 2000.