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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medically reviewed by WellAlly Editorial TeamLast reviewed October 19, 2026Editorial policy
First Aid21 min read

First Aid for Allergic Reactions

Published: October 19, 2026Updated: October 19, 2026

Allergic reactions occur when the immune system overreacts to a harmless substance, ranging from mild hives to life-threatening anaphylaxis. Recognizing warning signs such as facial swelling, wheezing, and dizziness is critical for immediate intervention. Promptly using an epinephrine auto-injector and seeking emergency medical care can prevent fatal complications.

Quick Summary

Immediately administer epinephrine and call 911 if an allergic reaction causes breathing difficulty, throat tightness, or dizziness.

Important Medical Disclaimer

This guide is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult with qualified healthcare providers for medical concerns.

Step-by-Step Guide

1

Assess for Signs of Anaphylaxis

Quickly check whether the reaction is mild or severe. Mild symptoms include localized itching, a rash, or a runny nose. Severe symptoms (anaphylaxis) involve throat tightness, wheezing, difficulty breathing, lip or tongue swelling, vomiting, or dizziness.

Important: Treat any respiratory difficulty, throat tightness, or sudden lightheadedness as a medical emergency immediately.

2

Administer Epinephrine Immediately

If the individual shows signs of anaphylaxis or has a known severe allergy, immediately use their prescribed epinephrine auto-injector. Push the auto-injector firmly against the outer mid-thigh until it clicks, and hold it firmly in place according to device instructions (typically 2 to 3 seconds).

Important: Never delay epinephrine administration to give oral antihistamines, as epinephrine is the only first-line medication capable of reversing airway obstruction and cardiovascular collapse.

3

Call Emergency Services (911)

Dial 911 or your local emergency number right away after delivering epinephrine, or immediately if severe symptoms arise and no injector is available. State clearly to the operator that the person is having an acute anaphylactic reaction and report whether epinephrine was administered.

4

Position the Person Safely

Lay the person flat on their back and elevate their legs approximately 12 inches to help maintain blood flow to vital organs. If the person is vomiting, turn them onto their side into the recovery position to keep the airway clear. If they are struggling to breathe, allow them to sit upright if it helps their breathing.

Important: Do not force the person to stand up or walk, as sudden upright positioning during anaphylaxis can cause a catastrophic drop in blood pressure.

5

Remove the Trigger if Possible

If the reaction was caused by an insect sting, quickly scrape the stinger off the skin using a fingernail or plastic card rather than squeezing it. If triggered by food or medication, ensure no more of the substance is ingested and gently wipe away any visible residue from the mouth.

6

Monitor and Prepare a Second Dose

Keep a constant watch on the person's breathing, pulse, and level of consciousness while awaiting emergency responders. If severe symptoms persist, return, or fail to improve after 5 to 10 minutes, administer a second epinephrine dose using a fresh auto-injector in the opposite thigh.

7

Manage Mild Symptoms with Antihistamines

For strictly mild, localized symptoms without any breathing problems, swelling of the face, or lightheadedness, an oral second-generation antihistamine (such as cetirizine or loratadine) can relieve itching and hives. Continue monitoring the person closely for several hours, as mild symptoms can occasionally progress into systemic reactions.

Important: Oral antihistamines do not treat anaphylaxis and will not open constricted airways or raise dangerously low blood pressure.

Frequently Asked Questions

Can I give an antihistamine instead of an EpiPen during a severe reaction?
No. Antihistamines take 30 to 60 minutes to take effect and cannot reverse life-threatening symptoms like throat swelling or low blood pressure. Epinephrine works within seconds and is the only proven first-line treatment for anaphylaxis.
What should I do if I am not sure whether a reaction is anaphylaxis?
When in doubt, use the epinephrine auto-injector. Epinephrine is very safe when given in emergency doses, and the potential risks of unnecessary administration are minor compared to the fatal risk of untreated anaphylaxis.
Why is an emergency room visit required if the epinephrine worked?
Epinephrine wears off after 15 to 20 minutes, and up to 20% of patients experience a biphasic reaction—a second wave of severe anaphylactic symptoms that occurs hours later without any additional exposure to the allergen.
How should an epinephrine auto-injector be stored?
Store auto-injectors at room temperature (68°F to 77°F or 20°C to 25°C) away from extreme heat, direct sunlight, and freezing conditions. Avoid keeping them in car glove compartments or refrigerators, as extreme temperatures can degrade the medication.
  1. 1
    Mayo ClinicSource
  2. 2
    NHSSource
  3. 3
    MedlinePlus (NIH)Source
  4. 4
    CDC NIOSHSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed October 19, 2026. · Read our editorial policy