Anaphylaxis; Anaphylaxis - first aid
Allergic reactions are sensitivities to substances called allergens that come into contact with the skin, nose, eyes, respiratory tract, and gastrointestinal tract. They can be breathed into the lungs, swallowed, or injected.
Allergic reactions are common. The immune response that causes an allergic reaction is similar to the response that causes hay fever. Most reactions happen soon after contact with an allergen.
Many allergic reactions are mild, while others can be severe and life threatening. They can be confined to a small area of the body, or they may affect the entire body. The most severe form is called anaphylaxis or anaphylactic shock. Allergic reactions occur more often in people who have a family history of allergies.
Substances that don't bother most people (such as venom from bee stings and certain foods, medicines, and pollens) can trigger allergic reactions in certain people.
First-time exposure may produce only a mild reaction. Repeated exposures may lead to more serious reactions. Once a person has had an exposure or an allergic reaction (and thus is sensitized to an allergen), even a very limited exposure to a very small amount of allergen can trigger a severe reaction.
Most severe allergic reactions occur within seconds or minutes after exposure to the allergen. Some reactions can occur after several hours. In very rare cases, reactions develop after 24 hours.
Anaphylaxis is a sudden and severe allergic reaction that occurs within minutes or hours of exposure. Immediate medical attention is needed for this condition. Without treatment, anaphylaxis can get worse very quickly and lead to death within 15 minutes.
Common allergens include:
Common symptoms of a mild allergic reaction include:
Symptoms of a moderate or severe reaction include:
For a mild to moderate reaction:
Calm and reassure the person having the reaction. Anxiety can make symptoms worse.
Try to identify the allergen and have the person avoid further contact with it.
For a severe allergic reaction (anaphylaxis):
Check the person's airway, breathing, and circulation (the ABC's of Basic Life Support). A warning sign of dangerous throat swelling is a very hoarse or whispered voice, or coarse sounds when the person is breathing in air. If necessary, begin rescue breathing and CPR.
If a person is having an allergic reaction:
Contact for medical assistance (911 or the local emergency number) right away if:
To prevent allergic reactions:
Barksdale AN, Ross W. Allergy, anaphylaxis, and angioedema. In: Walls RM, ed. Rosen's Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 106.
Custovic A, Tovey E. Allergen control for prevention and management of allergic diseases. In: Burks AW, Holgate ST, O'Hehir RE, et al, eds. Middleton's Allergy: Principles and Practice. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 84.
Higgins T. Allergic reaction. In: Higgins T, ed. Medicine for the Outdoors. 7th ed. Philadelphia, PA: Elsevier; 2024:78-79.
Shaker MS, Wallace DV, Golden DBK, et al. Anaphylaxis-a 2020 practice parameter update, systematic review, and grading of recommendations, assessment, development and evaluation (GRADE) analysis. J Allergy Clin Immunol. 2020;145(4):1082-1123. PMID: 32001253 pubmed.ncbi.nlm.nih.gov/32001253/.
BACK TO TOPReview Date: 3/31/2024
Reviewed By: Deborah Pedersen, MD, MS, Allergy & Asthma Care, PC, Taunton, MA. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
Health Content Provider
06/01/2025
|
A.D.A.M., Inc. is accredited by URAC, for Health Content Provider (www.urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics. This site complied with the HONcode standard for trustworthy health information from 1995 to 2022, after which HON (Health On the Net, a not-for-profit organization that promoted transparent and reliable health information online) was discontinued. |
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- 2024 A.D.A.M., a business unit of Ebix, Inc. Any duplication or distribution of the information contained herein is strictly prohibited.