Allergic Reaction and Anaphylaxis: Emergency Response

Guide to recognizing and treating allergic reactions and life-threatening anaphylaxis.

10 min readLast updated: 2026-02-17

Quick Facts

Onset
Anaphylaxis develops within minutes of exposure
Treatment
Immediate epinephrine injection is life-saving
Common Triggers
Foods, medications, insect stings, latex

Overview: Allergic Reactions and Anaphylaxis

Allergic reactions range from mild (localized itching or rash) to severe (anaphylaxis—life-threatening systemic reaction). Anaphylaxis is a medical emergency requiring immediate epinephrine treatment .

Recognition and rapid response save lives; any delay worsens outcomes.

Key Information
Anaphylaxis involves multiple organ systems and develops over minutes. Initial symptoms (itching, flushing, stomach cramps) may progress rapidly to airway swelling, breathing difficulty, hypotension, and loss of consciousness. Early epinephrine treatment is critical.

Mild-Moderate Allergic Reactions

Localized reactions—itchy rash, facial swelling from food contact—respond to antihistamines and observation. Allergic rhinitis (hay fever) responds to antihistamines and nasal corticosteroids. Mild urticaria (hives) without systemic symptoms often resolves with antihistamines.

Anaphylaxis Signs

Skin manifestations include flushing, urticaria (hives), and pruritus. Respiratory symptoms include wheezing, shortness of breath, stridor, and airway swelling. Gastrointestinal symptoms include cramping, vomiting, diarrhea, and abdominal pain. Cardiovascular symptoms include hypotension, dizziness, syncope, and cardiac arrest.

Anaphylaxis Emergency Response

Call emergency services immediately—before administering first aid. Have person lie down (unless vomiting or having breathing difficulty). Inject epinephrine intramuscularly into outer thigh through clothing if necessary . Repeat epinephrine after 5-15 minutes if symptoms persist. Remove allergen source if identifiable.

After Epinephrine Administration

Monitor continuously for symptom recurrence (biphasic anaphylaxis occurs in 10-20% of cases). Transport to emergency department for observation; IV fluids, additional medications, and ongoing monitoring are indicated. Do not discharge without medical evaluation.

Warning
Do not delay epinephrine for any reason. Epinephrine has excellent safety profile; benefits far outweigh risks. Delay in treatment significantly increases mortality. Never leave person alone after anaphylaxis; continuous monitoring is essential.
Clinical Note
Individuals with food or medication allergies should carry epinephrine auto-injectors at all times. Teach family members and friends proper auto-injector use. Medical alert identification helps emergency responders. After anaphylaxis, allergy testing and long-term management planning prevent future episodes.

Prevention

Avoid known allergens meticulously. Read food labels carefully. Question restaurants about food ingredients. Wear medical alert identification. Maintain epinephrine in accessible location. Educate caregivers about allergen avoidance and emergency response.

Sources

  1. [1]American Academy of Allergy, Asthma & Immunology. "Anaphylaxis: A Practice Parameter Update." Annals of Allergy, Asthma & Immunology, 2015.
  2. [2]Sampson HA et al.. "Anaphylaxis: Recognition and Management." Journal of Allergy and Clinical Immunology, 2016.

Medically reviewed by

Medical Review Team, Emergency Medicine

Last updated: 2026-02-17Sources: 2

The content on Medical Atlas is for informational purposes only. It is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider.