A food allergy reaction can begin as an itch and end as cardiac arrest. Anaphylaxis is the most severe form of allergic reaction and is a systemic, IgE-mediated immune response that causes simultaneous collapse of multiple organ systems within minutes of allergen exposure. It is not an exaggeration of a mild allergic reaction; it is a fundamentally different physiological event. Adrenaline is the only treatment that reliably reverses it, and a delay of even minutes worsens the outcome. Food is the leading trigger of anaphylaxis in India, and the majority of fatal reactions occur outside the hospital. This article explains what to do if you face a food allergy.

Common Foods That Trigger Anaphylaxis

Any food protein can trigger an allergic response. The following causes the majority of serious reactions:

• Peanuts
• Tree nuts like cashews, almonds, walnuts, and pistachios
• Shellfish and crustaceans like prawns, crabs, and lobster
• Fish like tuna, salmon, and mackerel
• Cow's milk - the most common food allergy in children under three
• Eggs predominantly from egg white protein; common in children, frequently outgrown
• Wheat causes an immediate-onset IgE-mediated response, distinct from coeliac disease
• Sesame.

Warning Signs and Symptoms of Food Allergy

Anaphylaxis typically develops within minutes of allergen ingestion. Biphasic reactions, a second wave of symptoms 4–12 hours after apparent resolution, occur in some cases. Progression is rapid:

• Generalised urticaria (hives), angioedema of lips, tongue, and face, flushing and generalised itching
• Throat tightness, stridor, or hoarseness (laryngeal oedema) causing upper airway compromise
• Wheeze and breathlessness
• Rapid, weak pulse and falling blood pressure
• Dizziness, collapse, or loss of consciousness
• Abdominal cramping, vomiting, and diarrhoea.

Anaphylaxis is diagnosed when two or more organ systems are involved after allergen exposure as skin reactions alone do not constitute anaphylaxis.

First Aid for Food Allergy (Anaphylaxis)

Speed is everything. The first aid sequence is:

• Administer adrenaline immediately: Auto-injector (EpiPen or equivalent) into the outer mid-thigh without delay. A second dose after 5-15 minutes if symptoms worsen. Adrenaline is not optional; it is the only first-line treatment.
• Call emergency services simultaneously: Do not wait to see if the reaction progresses. Every anaphylactic reaction requires hospital assessment even if adrenaline resolves symptoms as biphasic reactions can develop.
• Position correctly: 
  • Breathing difficulty: sit upright.
  • Haemodynamic compromise: flat with legs elevated.
  • Pregnant: left lateral.
• Remove the allergen: Stop eating; do not induce vomiting as it is ineffective and risks aspiration.
• Begin CPR if there is no pulse: Anaphylaxis cardiac arrest is reversible with early CPR and adrenaline. Continue until emergency services arrive.
• Do not give antihistamines as first-line treatment: They treat urticaria but do not reverse anaphylaxis. Using them instead of adrenaline is dangerous.

When to Seek Emergency Care for Food Allergy

Call emergency services and go to the emergency department for every suspected anaphylactic reaction without exception. Specific indications:

• Any throat tightness, voice change, or stridor after food ingestion
• Breathlessness or wheeze following allergen exposure
• Dizziness, rapid pulse, or collapse
• Any reaction involving two or more organ systems simultaneously
• Known previous anaphylaxis even a 'mild' current reaction can escalate unpredictably
• Reaction in a child
• EpiPen has been used
• No EpiPen available and the reaction is worsening.

Emergency Treatment at the Hospital for Food Allergy

At the hospital, treatment involves:

• IV adrenaline: When auto-injector adrenaline has been given pre-hospital or IM adrenaline is insufficient, IV adrenaline infusion (1 mcg/kg/min, titrated to response) is commenced in refractory anaphylaxis under cardiac monitoring.
• IV access and fluids: Anaphylactic shock involves massive vasodilatation and relative hypovolaemia requiring volume replacement alongside vasopressor support.
• Oxygen: High-flow oxygen via non-rebreathe mask for hypoxaemia; nebulised salbutamol for bronchospasm not relieved by adrenaline.
• Antihistamines and corticosteroids: IV antihistamines and IV steroids are adjunctive and reduce urticaria, angioedema, and the risk of biphasic reaction.
• Airway management: Progressive laryngeal oedema that does not respond to adrenaline requires early intubation as delay leads to complete airway obstruction. Surgical cricothyroidotomy or emergency tracheostomy if intubation is impossible.
• Vasopressors: Noradrenaline or vasopressin infusion for refractory anaphylactic shock not responding to IV adrenaline and fluid resuscitation.
• Observation: All patients require a minimum of four to six hours of observation following reaction resolution for biphasic monitoring. Patients with severe reactions, incomplete response, or risk factors for biphasic reaction are admitted for 24 hours.

Do's and Don'ts During Food Allergy

Do's:

• Carry a prescribed adrenaline auto-injector at all times
• Administer adrenaline at the first sign of anaphylaxis
• Call emergency services after every adrenaline use, regardless of apparent recovery
• Wear a medical alert identification: bracelet, card, or digital record
• Inform restaurants and food preparers of allergens at the time of ordering

Don'ts:

• Do not give antihistamines instead of adrenaline
• Do not leave the patient alone during a reaction
• Do not allow the patient to stand if they feel faint or haemodynamically compromised
• Do not assume the reaction has resolved because adrenaline was given as biphasic reactions can be dangerous
• Do not take risks with unlabelled foods, shared kitchen equipment, or restaurants that cannot confirm allergen-free preparation

Diagnostic Tests for Food Allergy

Acute anaphylaxis is diagnosed clinically. Post-reaction and outpatient workup includes:

• Serum tryptase: Elevated within 1–3 hours of anaphylaxis. It is the most useful biomarker confirming mast cell activation.
• Skin prick testing: Small quantities of allergen extract applied to the forearm and a wheal-and-flare response confirms IgE sensitisation. It is performed 4–6 weeks after the reaction.
• Specific IgE (RAST) blood testing: Quantifies IgE antibodies against individual food allergens.
• Component-resolved diagnostics: Identifies specific allergenic proteins (e.g. Ara h 2 for peanut) to predict the severity of future reactions
• Oral food challenge: Supervised, graded exposure to the suspected allergen under hospital conditions; the definitive diagnostic test, used when sensitisation is uncertain
• Full blood count and ECG: In acute presentation to exclude concurrent conditions.

Complications of Untreated Food Allergy (Anaphylaxis)

An untreated food allergy can cause:

• Respiratory failure
• Anaphylactic shock
• Cardiac arrest
• Hypoxic brain injury
• Biphasic anaphylaxis.

Why Choose CARE Hospitals for Emergency Food Allergy Care

Anaphylaxis arriving at the emergency is a time-critical resuscitation scenario. The team must secure an airway that can be closed within minutes, manage distributive shock and monitor for biphasic reaction over hours. CARE Hospitals emergency departments are equipped with adrenaline infusion protocols, immediate airway management capability including surgical airway access and the ICU infrastructure to manage refractory anaphylactic shock. For paediatric anaphylaxis, specialist paediatric emergency teams manage weight-based adrenaline dosing and post-reaction observation with age-appropriate protocols. Following discharge, CARE's allergy clinic provides structured follow-up like skin testing, specific IgE quantification, auto-injector training, and personalised action plans because the most important outcome after an anaphylactic episode is ensuring it never happens again without a plan.

Conclusion

Food-induced anaphylaxis can be fatal within minutes of allergen ingestion. The response has to match that urgency. Adrenaline first, calling emergency services immediately and hospital attendance regardless of apparent recovery. For patients with known food allergy, carrying two auto-injectors, wearing medical identification, and having an up-to-date emergency action plan are the minimum acceptable precautions. At CARE Hospitals, the emergency team is equipped to manage the full spectrum of anaphylactic severity ranging from the reaction that responds to a single adrenaline dose to the refractory case requiring ICU-level support.

FAQs

1. What is the first step in anaphylaxis?

Administer adrenaline via auto-injector into the outer mid-thigh immediately, without waiting to assess severity. Then call emergency services. Antihistamines and waiting are not alternatives to adrenaline; they are dangerous substitutes.

2. Can food allergies cause breathing problems?

Yes, bronchospasm and laryngeal oedema are among the most dangerous features of anaphylaxis. Bronchospasm causes wheezing and breathlessness; laryngeal oedema causes stridor, voice change, and throat tightness that can progress to complete airway obstruction without treatment.

3. Can anaphylaxis happen more than once?

Yes both as recurrent individual reactions from allergen re-exposure, and as biphasic anaphylaxis, where a second reaction occurs 4–12 hours after apparent resolution without further allergen contact. Biphasic reactions occur in up to 20% of cases and can be more severe than the initial episode.

4. What foods commonly cause allergies?

Peanuts, tree nuts (cashews, almonds, walnuts), shellfish, fish, cow's milk, eggs, wheat, mushrooms, and sesame account for the majority of serious food allergic reactions. In India, chickpeas, lentils, and mustard are additional significant triggers.

5. Can I prevent food allergies?

Established food allergies cannot be cured, but reactions can be prevented through strict allergen avoidance, clear labelling awareness, and communication with food preparers. Early introduction of allergenic foods in infancy has been shown to reduce the risk of developing peanut allergy in high-risk children. Oral immunotherapy under specialist supervision can desensitise selected patients to specific allergens.

CARE Medical Team