Guide — Emergency Nursing
Anaphylaxis Management Guide
Recognition criteria, epinephrine-first protocol, dosing and route, airway management priorities, secondary medications, biphasic reaction, and nursing priorities for emergency anaphylaxis care.
9 min read · Emergency Nursing
Educational use only. Anaphylaxis is a life-threatening emergency. Follow institutional emergency protocols and provider orders. Always call for help immediately. This material supports nursing education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional policy, or medical direction. Always follow facility protocols and current provider orders.
What Is Anaphylaxis?
Definition: A severe, life-threatening, systemic hypersensitivity reaction involving multiple organ systems, typically IgE-mediated. Mast cell and basophil degranulation releases histamine, tryptase, and other mediators → vasodilation, increased vascular permeability, bronchospasm, and mucus production.
Onset: Usually within minutes of exposure (faster onset = more severe reaction). Food allergies may have 30-minute delay. Exercise-induced anaphylaxis develops over longer period.
Systems affected: Skin/mucosa (urticaria, angioedema, flushing) + respiratory (wheeze, stridor, dyspnea) + cardiovascular (hypotension, tachycardia, syncope) + GI (nausea, vomiting, abdominal cramps) + neurological (altered mental status, sense of doom)
Common Triggers
| Category | Common Examples |
|---|---|
| Foods | Peanuts, tree nuts, shellfish, fish, milk, eggs, wheat, soy |
| Medications | Penicillin/beta-lactams, NSAIDs, aspirin, sulfonamides, contrast dye, ACE inhibitors (angioedema) |
| Insect venom | Bee, wasp, hornet, fire ant stings |
| Latex | Latex gloves, catheters, condoms — especially high risk in healthcare workers and patients with spina bifida |
| Exercise-induced | Exercise alone or in combination with specific foods (exercise-induced anaphylaxis) |
| Idiopathic | No identifiable trigger found in ~20% of cases |
Recognition Criteria
Anaphylaxis is likely if ANY of these 3 scenarios is met:
Scenario 1 (most common)
Acute onset of skin/mucosal involvement PLUS respiratory compromise or cardiovascular collapse
Example: Hives + wheezing; angioedema + hypotension
Scenario 2
Exposure to likely allergen + TWO OR MORE of: skin/mucosal symptoms, respiratory compromise, cardiovascular collapse, or GI symptoms
Example: Known bee allergy + hypotension + nausea after sting
Scenario 3
Exposure to KNOWN allergen + reduced BP alone
Example: Known peanut allergy + systolic BP drop of >30% from baseline
Clinical note: Skin symptoms (urticaria, flushing) may be ABSENT in up to 20% of anaphylaxis cases — do not rule out anaphylaxis because skin is clear. Cardiovascular collapse without skin findings can still be anaphylaxis.
Treatment Protocol — Step by Step
1 — EPINEPHRINE (FIRST AND ALWAYS)
Timing: Immediately
Action: Epinephrine 0.3–0.5 mg (0.3–0.5 mL of 1:1000) IM into the lateral thigh (vastus lateralis). Repeat every 5–15 minutes if no improvement.
Rationale: Reverses vasodilation, bronchoconstriction, and capillary leak simultaneously. Only drug that addresses all components of anaphylaxis.
Key point: No contraindications to epinephrine in anaphylaxis — do NOT withhold. IV only for cardiac arrest or profound refractory anaphylaxis.
2 — Position
Timing: Simultaneous with epinephrine
Action: Supine with legs elevated (Trendelenburg or legs up). Do NOT sit up or stand — increases risk of cardiovascular collapse.
Rationale: Maximizes venous return; prevents sudden cardiovascular collapse from position change ('empty ventricle syndrome').
Key point: If respiratory distress → allow patient to sit up. Pregnant → left lateral tilt to relieve aortocaval compression.
3 — Oxygen & Airway
Timing: Simultaneously
Action: High-flow O₂ via non-rebreather mask (10–15 L/min). Prepare for intubation: angioedema can progress rapidly. Continuous SpO₂ monitoring.
Rationale: Compensates for V/Q mismatch from bronchoconstriction and airway edema.
Key point: Call anesthesia early if stridor or voice changes — intubation becomes impossible once severe angioedema develops.
4 — IV Access & Fluids
Timing: Immediately
Action: Two large-bore IV lines. IV NS bolus 1–2 liters rapidly for hypotension. Continue boluses as needed (may require 4–6 L).
Rationale: Anaphylaxis causes massive fluid shifts out of vasculature — require aggressive volume replacement.
Key point: Fluid bolus is the second most important intervention after epinephrine for cardiovascular collapse.
5 — H1 Antihistamine
Timing: After epinephrine (secondary)
Action: Diphenhydramine (Benadryl) 25–50 mg IV or IM.
Rationale: Relieves urticaria and pruritus. Does NOT stop the reaction — only epinephrine does.
Key point: Do NOT give antihistamine INSTEAD of epinephrine — antihistamines do not reverse bronchoconstriction or cardiovascular collapse and act too slowly.
6 — H2 Antihistamine
Timing: After epinephrine (secondary)
Action: Ranitidine 50 mg IV or famotidine 20 mg IV.
Rationale: Additive benefit to H1 blockade for skin symptoms; may help with cardiovascular effects.
Key point: Secondary agent only; never substitute for epinephrine.
7 — Corticosteroids
Timing: After epinephrine (secondary)
Action: Methylprednisolone 125 mg IV or hydrocortisone 200 mg IV.
Rationale: May prevent biphasic reaction (evidence mixed). Reduces late-phase inflammation.
Key point: Slow onset (4–8 hours for full effect) — does NOT help the acute reaction. Secondary agent only.
8 — Bronchodilator
Timing: If bronchospasm persists after epinephrine
Action: Albuterol (salbutamol) nebulized — adjunct for bronchospasm. Does NOT replace epinephrine.
Rationale: Targets bronchospasm specifically; less cardiac effect than epinephrine.
Key point: Albuterol does not reverse anaphylaxis — epinephrine is still required.
9 — Glucagon
Timing: If patient on beta-blockers and refractory hypotension
Action: Glucagon 1–5 mg IV over 5 minutes, then infusion.
Rationale: Beta-blockers block epinephrine effects — glucagon acts via non-adrenergic pathway to increase heart rate and contractility.
Key point: Key NCLEX point: beta-blocker patients may not respond to epinephrine alone — add glucagon.
Biphasic Anaphylaxis
Definition: A second reaction occurring after apparent resolution of initial anaphylaxis, WITHOUT further allergen exposure. Can be as severe as or more severe than the initial reaction.
| Timing | 8–72 hours after initial reaction (most within 8–12 hours) |
| Incidence | ~5–20% of anaphylaxis cases; higher risk with delayed epinephrine administration, severe initial reaction, or unknown trigger |
| Observation period | 4–8 hours (minimum) after apparent resolution; 24 hours for severe reactions or high-risk patients |
| Discharge teaching | Return immediately if symptoms recur. Prescribe epinephrine auto-injector (EpiPen) × 2. Allergist referral. Medical alert bracelet. |
NCLEX Pearls
Epinephrine FIRST — always, no exceptions. Antihistamines and steroids are secondary. Delay in epinephrine = increased mortality.
Route: IM lateral thigh (vastus lateralis) — faster absorption than deltoid. IV route is reserved for cardiac arrest or refractory anaphylaxis with IV access.
Concentration matters: IM anaphylaxis dose = 1:1000 (0.3–0.5 mL). IV cardiac arrest dose = 1:10,000. These are 10× different — never confuse them.
Supine with legs elevated (not sitting up). Exception: respiratory distress → elevate head.
Beta-blocker patients: May not respond to epinephrine — give glucagon.
Antihistamines do NOT stop anaphylaxis. They relieve itching and hives but do not reverse bronchoconstriction or cardiovascular collapse.
Biphasic reaction: Observe for 4–8 hours minimum after resolution. Discharge with 2 EpiPens and return precautions.
"Sense of doom" (feeling of impending death) is a classic early symptom — take it seriously.
Related Resources
Standards & sources
Fact-checked Jun 20, 2026This page is written to align with Emergency Nurses Association (ENA) · AHA ACLS / PALS Guidelines · Advanced Trauma Life Support (ATLS). It is an educational summary, not a citation of any single document — always verify specific doses, values, and protocols against current guidelines and your facility policy. How we source content →