Please donate! Funds go solely to hosting and development costs that allow medical practitioners around the globe to freely access WikEM.
Acute allergic reaction
From WikEM
(Redirected from Allergic reactions)
Contents
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
- Asthma exacerbation
- Anxiety attack
- Scombroid
- Cold urticaria
- Contrast induced allergic reaction
- Shock
- Transfusion reaction
- Carcinoid syndrome
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]
- 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
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.