Frequently Asked Questions
Is anaphylaxis the same as a severe allergy?
Not exactly. Anaphylaxis is a specific, systemic allergic reaction involving multiple organ systems that can be life-threatening. A severe allergy is broader and may include anaphylaxis, but also severe localised reactions. The distinction matters clinically because anaphylaxis requires adrenaline; a severe localised reaction does not.
Can anaphylaxis happen without a known allergy?
Yes. First episodes of anaphylaxis can occur without any prior history of allergy to the triggering substance. This is why anaphylaxis after eating new foods, starting new medications, or receiving injections should always be taken seriously.
Can antihistamines prevent anaphylaxis?
No. Antihistamines (like cetirizine or loratadine) are suitable for mild allergic reactions such as hay fever and mild hives. They work too slowly and incompletely to reverse anaphylaxis. Using an antihistamine instead of adrenaline in anaphylaxis is dangerous.
What is a biphasic reaction?
A biphasic reaction is a second wave of anaphylaxis that occurs hours after the initial episode appears to have resolved, without any further exposure to the trigger. It occurs in approximately 5–20% of anaphylaxis cases. This is the reason all anaphylaxis patients require hospital observation even after apparent recovery.
My child had anaphylaxis at school. What should we do?
Work with the school to develop a written emergency action plan, ensure at least two members of staff are trained to use the auto-injector, store the auto-injector in an accessible location (not locked away), and ensure the school is briefed on all known triggers. In India, awareness of food allergy protocols in schools is still developing — proactive parent communication is essential.
This article is for educational purposes. It does not constitute medical advice. In any suspected anaphylaxis, call emergency services immediately. Dr. Keerthi Vardhan, MD (Internal Medicine), DM (Clinical Immunology & Rheumatology), Assistant Professor, NIMS Hospital, Hyderabad.