🚑 EmergencyImmunology / EmergencyStudentInternResident

Anaphylaxis

Also known as: severe allergic reaction · anaphylactic shock

Acute, life-threatening systemic hypersensitivity with airway, breathing or circulation compromise within minutes of a trigger. Intramuscular adrenaline is the immediate, life-saving treatment.

Source · Reviewed 2026-08-15 · v1.0— AI-assisted draft — verify against the cited guideline before clinical use.

⚕️ Education only — not medical advice. Verify against the latest official guideline and your local protocol; confirm every drug dose against the cited source before clinical use.

Who gets it

Anyone exposed to a trigger — foods (nuts, egg, milk, seafood), drugs (penicillins, NSAIDs, anti-snake venom, contrast), insect stings or latex. Prior reactions and asthma increase severity.

Red flags — escalate / refer

Sudden onset after a likely trigger PLUS any Airway (tongue/throat swelling, stridor, hoarse voice), Breathing (wheeze, hypoxia) or Circulation (hypotension, collapse) problem = anaphylaxis → give IM adrenaline NOW.
Biphasic reactions can recur hours later → observe after recovery.
Do not stand or sit the patient up suddenly if hypotensive — it can precipitate cardiac arrest.

Work-up / diagnosis

1Diagnose clinically — do NOT delay adrenaline for any test.
2Remove/stop the trigger (e.g. stop the infusion); call for help.
3After stabilisation, a timed serum tryptase can support the diagnosis; refer to allergy to identify the trigger and provide an adrenaline auto-injector plan.

Management — overview

Give intramuscular adrenaline into the anterolateral thigh immediately — the single most important step; repeat every 5 minutes if no improvement.
Position: lie flat with legs raised (sit up only if breathing is difficult; left lateral if pregnant). Give high-flow oxygen.
Insert a large-bore IV line and give a rapid crystalloid fluid bolus for hypotension.
Adjuncts come AFTER adrenaline, never instead: inhaled bronchodilator for wheeze; antihistamine/steroid are second-line and not life-saving.
Observe for a biphasic reaction; discharge with an adrenaline auto-injector, a written action plan and allergy referral.

In-depthFull dosing & advanced protocol

Drug dosing

Adrenaline (epinephrine) 1 mg/mL (1:1000)

First-line — give immediately

Adult dose: 0.5 mg (0.5 mL) IM; repeat every 5 min as needed
Paediatric: 0.01 mg/kg IM (max 0.5 mg): ~150 µg if <6 y, 300 µg if 6–12 y
Route: Intramuscular, anterolateral thigh

Caution: IM (not IV) for anaphylaxis. IV adrenaline only by experts with monitoring (refractory shock/arrest).

WHOWHO Model List of Essential Medicines (electronic EML) (2025 (24th)) ↗

IV crystalloid (0.9% saline or Ringer's lactate)

Hypotension / shock

Adult dose: 500–1000 mL rapid bolus, titrate to response
Paediatric: 10 mL/kg rapid bolus, repeat as needed
Route: Intravenous

WHOWHO Model List of Essential Medicines (electronic EML) (2025 (24th)) ↗

Adjuncts (second-line, after adrenaline)

Symptom relief — not a substitute for adrenaline

Adult dose: Salbutamol nebuliser for bronchospasm; antihistamine/hydrocortisone are optional and non-urgent
Route: Inhaled / IV

ICMRStandard Treatment Workflows (STWs), India — Dept. of Health Research & ICMR (2022+) ↗

Refractory & special situations

Refractory anaphylaxis (no response to repeated IM doses): an adrenaline infusion by an experienced clinician with monitoring; consider senior/ICU help.
Patients on beta-blockers may respond poorly — glucagon is an option.
Pregnancy: manage in the left-lateral position; the priorities are unchanged.

ICMRStandard Treatment Workflows (STWs), India — Dept. of Health Research & ICMR (2022+) ↗

References

Guidelines change. If something here is out of date, tell us — we keep these current.

🚩 Report outdated / suggest update

More protocols

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👤 Who gets it

🚩 Red flags — escalate / refer

🔎 Work-up / diagnosis

🧭 Management — overview

💊 Drug dosing

Adrenaline (epinephrine) 1 mg/mL (1:1000)

IV crystalloid (0.9% saline or Ringer's lactate)

Adjuncts (second-line, after adrenaline)

📈 Refractory & special situations

📚 References

More protocols

👤 Who gets it

🚩 Red flags — escalate / refer

🔎 Work-up / diagnosis

🧭 Management — overview

💊 Drug dosing

Adrenaline (epinephrine) 1 mg/mL (1:1000)

IV crystalloid (0.9% saline or Ringer's lactate)

Adjuncts (second-line, after adrenaline)

📈 Refractory & special situations

📚 References

More protocols

Who gets it

Red flags — escalate / refer

Work-up / diagnosis

Management — overview

Drug dosing

Refractory & special situations

References

Who gets it

Red flags — escalate / refer

Work-up / diagnosis

Management — overview

Drug dosing

Refractory & special situations

References