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Last Updated January 2023 | This article was created by editorial staff and reviewed by Robert "Chuck" Rich, Jr., MD, FAAFP

What is anaphylaxis?

Anaphylaxis is a life-threatening allergic reaction. It occurs when you are exposed to something you are severely allergic to. Immediate medical attention is required.

Anaphylactic reactions can range in severity. However, most allergic reactions don’t lead to anaphylaxis.

Symptoms of anaphylaxis

Symptoms vary based on your degree of allergy and the amount of exposure. They range from mild to severe. Possible symptoms or problems include:

  • Swelling in your mouth, throat, or other body part
  • Hives, rash, or itchy skin
  • Pale skin, or skin that is red and warm (flushed)
  • Trouble breathing or gasping for breath
  • A tight feeling in your chest
  • Dizziness
  • Fainting
  • Stomach pain
  • Nausea, vomiting, or diarrhea
  • A feeling of anxiety
  • Low blood pressure
  • Cardiac arrest

What causes anaphylaxis?

Anaphylaxis is most often caused by exposure to an allergen. During a normal reaction, your body produces antibodies to fight the allergen. During a severe reaction, your immune system can panic. This leads to anaphylaxis, which is very dangerous.

An allergy to peanuts, for example, can result in anaphylaxis. In order to have an anaphylactic reaction to peanuts, a person must have ingested the protein. The smell of peanuts may cause anxiety, but it doesn’t cause a whole-body reaction.

Although peanut allergies are common, new research suggests they may be preventable in most cases. Recent National Institutes of Allergy and Infectious Diseases guidelines say that introducing small amounts of peanut foods to children as early as 4 to 6 months may prevent the allergy. These guidelines have been endorsed by the American Academy of Pediatrics and championed by the AAFP. New peanut-based products are now available for children within that age range. Talk to your family doctor before introducing this food.

According to Dietary Guidelines for Americans, healthy eating from birth through 23 months can reduce the risk of chronic disease, including lowering the risk of peanut allergy.

Allergens that may cause anaphylaxis include:

  • Foods, such as shellfish, nuts, peanuts, eggs, and fruits
  • Medicines, such as antibiotics, aspirin, over-the-counter pain relievers, allergy shots, and contrast dye for imaging procedures
  • Latex or rubber found in surgical gloves, medical supplies, and many products in your home
  • Insect stings, such as from bees, wasps, hornets, yellow jackets, sawflies, and fire ants

How is anaphylaxis diagnosed?

If you or someone around you has anaphylaxis, call 911 immediately. Call your doctor if you have milder symptoms of anaphylaxis. They will want to see you whether your symptoms are mild or severe. They can diagnose the cause of the reaction and provide treatment.

Can anaphylaxis be prevented or avoided?

Below are ways to help prevent or avoid anaphylaxis.

  • Alert all doctors about any allergies you have.
  • Tell your doctors if you have had anaphylaxis in the past. This should be noted in your medical chart.
  • Avoid eating or touching foods you are allergic to. Even tiny amounts can cause a severe reaction. Read the ingredient list on packaged foods. When eating out, tell the server or chef about your allergy.
  • If you are allergic to insect stings, wear protective clothing and insect repellent when you are outside.
  • Wear or carry a medical alert bracelet, keychain, or card. This will help doctors and health professionals who treat you in an emergency.
  • Carry an emergency anaphylaxis kit with you at all times. Your doctor can prescribe this. It contains medicine to reduce an allergic reaction once it starts. The medicine is called an epinephrine injector (EpiPen). Family, friends, and coworkers should know how to use it. A kit may also include an antihistamine, such as diphenhydramine (brand name: Benadryl).

Anaphylaxis treatment

Treatment for anaphylaxis should begin right away. If you see someone have a reaction, call 911 to get medical help. If the person has an emergency kit with an EpiPen, inject it into the muscle of their arm or leg. An EpiPen is a short-term treatment. The person still should go to the hospital for treatment and care. Certain allergies may require a series of desensitization shots.

Living with anaphylaxis

Most people who receive treatment live a normal, full life. If you do not get treatment and symptoms are severe, you could die. After treatment, you should have someone stay with you for 24 hours to make sure another attack does not occur. Talk to your doctor about how to prevent future attacks. They can prescribe an emergency kit and teach you how to use it. People who are likely to experience anaphylaxis may be more fearful in certain situations, such as trying new foods, venturing outdoors, etc.

Questions to ask your doctor

  • I have an allergy. Could I be at risk for anaphylaxis?
  • Do I need to wear a medical alert bracelet? Where do I get one?
  • What should I have in my emergency kit?
  • If I have had anaphylaxis, what is my risk of having it again?
  • How do I make sure that all members of my health care team know about my risk?
  • Can a person outgrow a peanut allergy?
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