Acute allergic reaction
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
Diagnosis
- Clinical
Management
- H1 agonist: Diphenhydramine 50mg IV/IM/PO
- H2 agonist: Famotidine 40mg OR ranitidine 150mg IV/IM/PO
- Improves urticaria but not angioedema at 2 hours[1]
- Consider corticosteroid: Solumedrol 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
- ↑ 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.