Anaphylaxis Management for Paramedics (UK Guide)

Anaphylaxis Management for Paramedics: A Practical UK Guide

Anaphylaxis is one of the most time-critical emergencies a paramedic will face in pre-hospital practice. A severe, life-threatening systemic hypersensitivity reaction, it can deteriorate within minutes if not recognised and treated promptly. This guide covers everything UK student paramedics need to know — from pathophysiology and recognition through to JRCALC-aligned drug treatment and post-resuscitation care.

Understanding the Pathophysiology

Anaphylaxis occurs when a sensitised individual is re-exposed to a specific allergen, triggering a massive IgE-mediated immune response. Mast cells and basophils degranulate, releasing histamine, prostaglandins, and leukotrienes. The result is a cascade of vasodilation, increased capillary permeability, bronchospasm, and mucosal oedema — all of which can rapidly compromise the airway, breathing, and circulation simultaneously.

Common triggers in the UK include peanuts and tree nuts, insect stings, medications (particularly penicillin-based antibiotics and NSAIDs), latex, and shellfish. However, in a significant proportion of cases no trigger is identified at the time of the emergency response.

Recognising Anaphylaxis in the Field

Rapid and accurate recognition is the cornerstone of effective anaphylaxis management. The Resuscitation Council UK defines anaphylaxis as likely when all three of the following criteria are met:

• Sudden onset with rapid progression of symptoms
• Life-threatening airway, breathing, or circulation problems
• Skin or mucosal changes (flushing, urticaria, angioedema) — present in over 80% of cases but absence does not rule out anaphylaxis

Clinical features you may encounter on scene include:

• Airway: Stridor, oropharyngeal swelling, hoarse voice, drooling
• Breathing: Wheeze, bronchospasm, tachypnoea, SpO₂ deterioration
• Circulation: Tachycardia, hypotension, pallor, reduced consciousness, cardiac arrest
• Skin: Urticaria, erythema, pruritus, angioedema of the face and lips
• Other: Nausea, vomiting, abdominal cramping, sense of impending doom

It is important not to wait for all features to be present. If the clinical picture is consistent with anaphylaxis, treat it as such — delay is dangerous.

JRCALC Treatment Pathway

The Joint Royal Colleges Ambulance Liaison Committee (JRCALC) guidelines provide the definitive framework for pre-hospital anaphylaxis management in the UK. The treatment approach follows an ABCDE structure, with adrenaline (epinephrine) as the cornerstone intervention.

Step 1: Remove the Trigger and Call for Help

Where safely possible, remove or stop the causative agent — for example, stopping an IV infusion if a drug reaction is suspected. Ensure the patient is in a position of comfort: sitting upright if they have airway or breathing compromise; lying flat with legs elevated if hypotension or shock is predominant. Do not allow patients to stand up suddenly, as this can precipitate cardiac arrest.

Step 2: Administer Intramuscular Adrenaline

Adrenaline (epinephrine) 1:1000 given intramuscularly is the first-line and most important treatment in anaphylaxis. It reverses vasodilation, reduces capillary permeability, causes bronchodilation, and has positive inotropic and chronotropic effects on the heart.

JRCALC-recommended doses by age group:

• Adult (over 12 years): 500 micrograms IM (0.5 ml of 1:1000)
• Child 6–12 years: 300 micrograms IM (0.3 ml of 1:1000)
• Child 6 months to 6 years: 150 micrograms IM (0.15 ml of 1:1000)
• Child under 6 months: 100–150 micrograms IM — seek medical direction

The preferred injection site is the anterolateral aspect of the middle third of the thigh. This site offers faster absorption than the deltoid, particularly in patients with reduced perfusion. If there is no improvement after 5 minutes, the dose can be repeated. Patients who have their own auto-injector (such as an EpiPen) may already have self-administered a dose — document this and factor it into your decision-making.

Step 3: High-Flow Oxygen and Airway Management

Administer high-flow oxygen at 15 L/min via a non-rebreather mask to all patients with anaphylaxis. Monitor SpO₂ and be prepared to assist ventilation. Early consideration of advanced airway management is essential if angioedema is progressing — once the airway is critically compromised, intubation may become impossible. Supraglottic airway devices or surgical airway may be required in extremis.

Step 4: IV Fluid Resuscitation

Establish IV access and administer a fluid challenge of 500–1000 ml sodium chloride 0.9% to adults experiencing haemodynamic compromise. In children, give 10 ml/kg and reassess. Fluids help counteract the massive vasodilation and third-spacing of fluid that accompanies anaphylaxis.

Step 5: Adjunct Medications

Following adrenaline and supportive care, adjunct medications may be used — though they are secondary to adrenaline and must never delay its administration:

• Chlorphenamine (antihistamine): 10 mg IV or IM in adults — reduces histamine-mediated effects
• Hydrocortisone: 200 mg IV or IM in adults — helps prevent biphasic reactions (delayed second wave of symptoms)
• Salbutamol: 5 mg nebulised — useful for persistent bronchospasm unresponsive to adrenaline

Anaphylaxis in Cardiac Arrest

If the patient deteriorates into cardiac arrest, commence standard CPR and follow the cardiac arrest algorithm. Adrenaline in cardiac arrest is given IV or IO at 1 mg (1:10,000) every 3–5 minutes as per ALS protocol. Consider early advanced airway management and aggressive fluid resuscitation. Extended resuscitation attempts are warranted in anaphylaxis, as reversible causes can be corrected.

Biphasic Reactions and Hospital Handover

All patients with suspected anaphylaxis must be transported to the emergency department regardless of clinical improvement. Biphasic reactions — a recurrence of anaphylaxis hours after the initial episode without re-exposure — occur in up to 20% of cases. During handover, clearly communicate the suspected trigger, timeline of symptoms, all drugs administered and doses, and the patient's response to treatment. Ensure the receiving team are aware if the patient has a history of anaphylaxis or carries an auto-injector.

Key Learning Points

• Adrenaline IM 1:1000 is always the first-line treatment — give it early
• Position the patient appropriately for their presenting features
• Repeat adrenaline after 5 minutes if there is no response
• Adjuncts such as chlorphenamine and hydrocortisone are secondary — never delay adrenaline for them
• All anaphylaxis patients require hospital assessment due to biphasic reaction risk
• Document everything clearly for handover and clinical governance