Use the adrenaline auto-injector first, then call 911 — in that order, not the other way round. Adrenaline is the only treatment that reverses anaphylaxis, delay is what makes it fatal, and there is no meaningful risk in giving it to someone who turns out not to need it. Antihistamines do not treat anaphylaxis. Neither does an inhaler.
Then go to an emergency room even if the person recovers completely, because reactions can return hours later after the adrenaline wears off.
Recognising anaphylaxis
It is a whole-body reaction, usually within minutes of exposure but sometimes up to a couple of hours. Suspect it when two or more body systems are involved, or when there is any breathing or circulation problem at all:
- Breathing — throat tightness, hoarse voice, a persistent cough, wheeze, difficulty breathing, noisy breathing
- Circulation — faintness, dizziness, pale or grey skin, collapse, a sense of impending doom
- Skin — hives, widespread flushing, swelling of lips, tongue, face or eyes
- Gut — sudden vomiting, cramping abdominal pain, diarrhoea
- In infants and small children — sudden floppiness, pallor, inconsolable crying, drooling
Swelling of the tongue or throat, or any difficulty breathing, is anaphylaxis regardless of what else is or is not happening.
What to do
- Give adrenaline immediately — outer thigh, through clothing if needed, hold for the time the device specifies.
- Call 911. Say “anaphylaxis” and say adrenaline has been given.
- Lie them flat with legs raised if they feel faint. Do not stand them up or walk them — a sudden drop in blood pressure on standing has caused deaths. If they are vomiting, lie them on their side. If breathing is the main problem, let them sit up.
- A second dose after 5 to 15 minutes if there is no improvement. Carry two injectors for this reason.
- Stay with them and keep the used device to hand over.
- Go to hospital even after a full recovery. Up to a fifth of reactions are biphasic — they return hours later, sometimes without a second exposure, and the second wave can be worse.
Never wait to see if it settles. The commonest factor in fatal food-allergy reactions is delayed adrenaline.
Allergy or intolerance?
Worth being clear, because the words get used interchangeably and the stakes differ enormously.
Allergy is an immune reaction. It can involve the skin, airway and circulation, can be triggered by a trace amount, and can be life-threatening.
Intolerance — lactose intolerance being the common example — is a digestive problem. It is genuinely unpleasant, it is dose-related, and it will not kill anyone.
Treating a real allergy as a preference is how people end up in our emergency room. Treating an intolerance as an allergy is how people restrict their diet unnecessarily. Testing sorts it out.
The nine major allergens
US labelling law requires declaration of: milk, eggs, peanuts, tree nuts, soy, wheat, fish, shellfish, and sesame — sesame was added in 2023, so packaging and recipes you relied on before then may not have flagged it.
In adults, shellfish, tree nuts, peanuts and fish are the usual culprits. In children, milk, egg and peanut dominate — and many children outgrow milk and egg allergy, while peanut, tree nut and shellfish allergies more often persist.
Living with it
Read every label, every time. Manufacturers reformulate without warning, and “may contain” warnings are voluntary and inconsistent.
Carry two auto-injectors, always, and check the expiry and that the liquid is clear. A device in a hot car is a real problem here — see expired medications.
Wear medical identification if the allergy is severe.
In restaurants, say “allergy” rather than “I don’t eat”, name the food, and ask about shared fryers and grills. Cross-contamination causes plenty of reactions in kitchens that thought they had handled it.
At school, make sure there is a written action plan, in-date medication, and staff who know where it is. See back-to-school health.
Teach children to speak up early, and to tell an adult the moment something feels wrong in the mouth or throat.
Two things that have changed
Early introduction now prevents allergy rather than causing it. Guidance reversed roughly a decade ago: introducing peanut and egg in infancy, around 4 to 6 months alongside other solids, substantially reduces the chance of developing those allergies. If you have a baby and a family history of allergy, ask us about the timing rather than following advice from the 2000s.
Oral immunotherapy exists. Carefully supervised, escalating doses can raise the threshold at which a reaction occurs — not a cure, and not for everyone, but a genuine option worth discussing with an allergist.
An Arizona note
Anaphylaxis here is not only food. Bee and wasp stings are a common trigger, and our scorpion and snake encounters can also produce allergic reactions on top of the venom itself — see scorpion stings and rattlesnake bites. If a sting has ever caused more than local swelling, you should be carrying adrenaline.
And keep injectors out of the car in summer. Heat degrades them, and the one time you need it is not when you want to discover that.
Where to go
Call 911 for any suspected anaphylaxis — after giving adrenaline.
Come to our Emergency Room — 9700 N. Saguaro Blvd, open 24 hours, no appointment — after any adrenaline use, after any reaction involving breathing or faintness, and for a reaction you are unsure about. We can observe for a biphasic reaction, which is the part that cannot be done at home. ER: (602) 671-7990.
Book our Medical Clinic for allergy testing, an action plan, auto-injector prescriptions and training, infant introduction advice, or an allergist referral: (602) 671-7981.
Sources
- American Academy of Allergy, Asthma & Immunology — Anaphylaxis
- FDA — Food allergen labelling, including sesame
- NIAID — Guidelines for peanut allergy prevention
- CDC — Food allergies in schools