Anaphylaxis: Recognition, Emergency Treatment & Prevention

Anaphylaxis is a rapid-onset, multisystem allergic reaction — life-threatening without immediate epinephrine.

Diagnostic Criteria (Any 1)

1. Acute skin/mucosa (hives, angioedema, flush) + respiratory compromise OR hypotension.
2. ≥2 systems after allergen exposure: skin, respiratory, GI, cardiovascular.
3. Hypotension after known allergen exposure.

Common Triggers

• Foods: Peanut, tree nut, shellfish, fish, milk, egg, wheat, soy, sesame.
• Hymenoptera stings (bee, wasp, fire ant).
• Medications: Penicillins, NSAIDs, biologics, NMBA.
• Latex, exercise (food-dependent).

Emergency Treatment

1. EPINEPHRINE IM (anterolateral thigh) — FIRST AND FAST. 0.3 mg (0.3 mL of 1 mg/mL) adult; 0.15 mg child <25 kg. Repeat q5–15 min if needed.
2. Call 911 / activate EMS.
3. Supine position (legs raised) — prevents empty ventricle syndrome.
4. O₂, IV fluids, albuterol (bronchospasm), H1/H2 blockers, steroids (adjuncts only — do not delay epi).

Post-Event

• Observation 4–6 hrs (biphasic reaction risk 1–20%).
• Prescribe 2 auto-injectors; train patient/family.
• Allergist referral: confirm trigger, skin/test, action plan, consider OIT/biologics.
• Medical ID.

Risk Factors for Severe/Fatal

• Asthma (poorly controlled), adolescence/young adult, delay in epi, upright posture, cardiovascular disease, β-blocker/ACEi use.

Epinephrine first, epinephrine fast, epinephrine always.