Anaphylaxis in the ED: Epinephrine First, Questions Later

-Case-
A 31-year-old woman rushes into the ED with her lips swelling and a rapidly spreading rash. She was stung by a bee while jogging, and within minutes developed hives, throat tightness, and shortness of breath. On arrival, her vitals are notable for HR of 118 bpm, a BP 82/50 mmHg, and she’s wheezing audibly. She’s anxious, flushed, and says, “I feel like I can’t breathe.”

-Evaluation-
Anaphylaxis is a severe, systemic hypersensitivity reaction that can rapidly progress to shock and death. It is most often IgE-mediated and commonly triggered by insect stings, foods (e.g., peanuts, shellfish), and medications (e.g., beta-lactams, NSAIDs).

• Anaphylaxis is highly likely when one of the following is present:
  1. Acute onset (minutes to hours) with skin/mucosal involvement plus either:
     • Respiratory compromise (dyspnea, wheeze, stridor)
     • Hypotension or signs of end-organ dysfunction
  2. Two or more of the following after exposure to likely allergen:
     • Skin/mucosal involvement
     • Respiratory compromise
     • Hypotension
     • GI symptoms (vomiting, diarrhea, cramping)
  3. Hypotension after exposure to known allergen (SBP <90 mmHg or >30% drop from baseline)

-Management-

1. Epinephrine first!
   • 0.3-0.5 mg IM (1:1000) into the lateral thigh
   • Repeat every 5-15 minutes as needed
   • Remember – there is no absolute contraindication to epinephrine in anaphylaxis!
2. Supportive Measures:
   • High-flow oxygen if our patient is hypoxic
   • IV fluids (1-2 L bolus) for hypotension
3. Adjunctive Therapies (AFTER epi):
   • Antihistamines: diphenhydramine 25-50 mg IV (H1) or ranitidine/famotidine (H2)
   • Steroids: methylprednisolone or dexamethasone (to prevent late-phase reaction)
   • Beta-agonists (e.g., albuterol) as needed for bronchospasm
4. Observe and Educate:
   • Monitor for biphasic reaction (repeat symptoms after resolution, typically within 8 hours)
   • Discharge with epinephrine auto-injector and strict return precautions
   • Refer to allergy specialist for definitive testing and prevention

-Fast Facts-

• Epinephrine is the first and most important treatment

• Anaphylaxis can occur without skin symptoms; watch for respiratory or circulatory collapse
• Steroids and antihistamines are supportive only, not definitive

Anaphylaxis is a time-critical diagnosis that rewards rapid action. Your job is to recognize it fast, reach for epinephrine early, and stabilize aggressively. And don’t wait for full criteria to develop – treat the moment the pattern emerges! In the ED, anaphylaxis is one of the few conditions where hesitation is the real danger.

Want to learn more? Read our in-depth study guide and listen to our podcast episodes on this topic!

Cheers,

Tamir Zitelny, MD

-References-

1. Campbell RL, Li JT, Nicklas RA, Sadosty AT. Emergency department diagnosis and treatment of anaphylaxis: a practice parameter. Ann Allergy Asthma Immunol. 2014;113(6):599-608. doi:10.1016/j.anai.2014.10.007
2. Simons KJ, Simons FE. Epinephrine and its use in anaphylaxis: current issues. Curr Opin Allergy Clin Immunol. 2010;10(4):354-361. doi:10.1097/ACI.0b013e32833b6e90
3. Lieberman P, Nicklas RA, Randolph C, et al. Anaphylaxis—a practice parameter update 2015. Ann Allergy Asthma Immunol. 2015;115(5):341-384. doi:10.1016/j.anai.2015.07.019
4. Sampson HA, Muñoz-Furlong A, Campbell RL, et al. Second symposium on the definition and management of anaphylaxis: summary report—Second National Institute of Allergy and Infectious Disease/Food Allergy and Anaphylaxis Network symposium. J Allergy Clin Immunol. 2006;117(2):391-397. doi:10.1016/j.jaci.2005.12.1303
5. Manivannan V, Decker WW, Stead LG, Li JT, Campbell RL. Visual representation of National Institute of Allergy and Infectious Disease and Food Allergy and Anaphylaxis Network criteria for anaphylaxis. Int J Emerg Med. 2009;2(1):3-5. doi:10.1007/s12245-008-0062-z