Anaphylaxis

Overview

What is anaphylaxis?

Anaphylaxis (an-ah-fi-LAK-sis) is a severe allergic reaction. It can be life-threatening if you don’t get treatment right away. Food allergies are one of the main causes of anaphylaxis.

What is an allergic reaction?

When you are allergic to something, your immune system overreacts by releasing chemicals like histamine. These chemicals cause symptoms such as itchy, watery eyes and a runny nose. Usually, the symptoms happen in one location of the body.

But in some people, the reaction is more severe, resulting in anaphylaxis. Symptoms include swelling, wheezing, shortness of breath and difficulty swallowing. An anaphylactic reaction affects several areas of the body at once.

What is anaphylactic shock?

A person who has an anaphylactic reaction can go into anaphylactic shock. Blood pressure drops severely. The bronchial tissues, which help carry air, swell. These reactions cause wheezing, shortness of breath and even loss of consciousness. Anaphylactic shock requires immediate treatment to save the person’s life.

How common is anaphylaxis?

Anaphylaxis is common in the United States. Existing data show it occurs in about one in 50 people. But many researchers believe the rate is even higher, possibly closer to one in 20 people.

Symptoms and Causes

What causes anaphylaxis?

Food allergies are one of the main causes of anaphylaxis. Foods that can cause this severe anaphylactic reaction include:

Other allergens (substances that cause allergies) that can lead to anaphylaxis include:

Does pollen cause anaphylaxis?

Pollen and other allergens that you breathe in rarely cause anaphylaxis.

What are the symptoms of anaphylaxis?

Anaphylaxis usually begins with severe itchiness in the eyes or face. Within a few minutes, you may start experiencing more severe symptoms, including:

If you notice symptoms, get medical help right away or use your allergy medication. Without treatment, more severe, life-threatening anaphylaxis symptoms may occur:

When do symptoms of anaphylaxis start?

Usually, symptoms start within five to 30 minutes of coming into contact with the allergen. For example, you might get stung by a bee or eat something with peanuts. But symptoms can sometimes start more than an hour later.

What is biphasic anaphylaxis?

Biphasic anaphylaxis is when you have a second wave of symptoms after the first symptoms go away. This second wave can be hours or even days after the first wave. About 20% of people who have anaphylaxis get biphasic anaphylaxis.

Diagnosis and Tests

How is anaphylaxis diagnosed?

If you’ve had an allergic reaction to food or insect stings (even a mild one), talk to your healthcare provider. A provider can often diagnose anaphylaxis based on your symptoms.

Taking this important step can protect your health and even save your life. It applies to anyone who’s had any type of allergic reaction. If you have, you face a greater risk of developing a severe anaphylactic reaction in the future.

Getting a diagnosis is necessary to get the treatment you need.

What tests can diagnose anaphylaxis?

An allergist (allergy specialist) may recommend testing your skin and blood. These tests can confirm the substances that cause severe reactions. A skin test places a small amount of the allergen on your skin to see if it causes a reaction. A blood test that measures tryptase can be helpful if obtained within one to three hours of the allergic reaction.

Management and Treatment

How is anaphylaxis treated?

If you’ve had allergic reactions to food or insect bites, your provider will prescribe an epinephrine (adrenaline) injection. Adrenaline treats the symptoms caused by the reaction.

You carry around the injector, about the size of a larger marker, wherever you go. If you experience an anaphylactic reaction, you inject yourself with the medication, usually in your thigh. These shots work quickly to reverse symptoms.

If symptoms don’t improve after five to 15 minutes, give yourself a second injection, if you have one available. After injecting yourself, get medical help or call 911. You need a medical evaluation after having an anaphylactic reaction.

How can I tell if someone is having an anaphylactic reaction?

Look for these signs, usually involving the nose, mouth, skin or digestive system:

  • Difficulty breathing.
  • Rash or swollen lips.
  • Signs of low blood pressure, such as a weak pulse, confusion or loss of consciousness.
  • Stomach symptoms, such as vomiting, diarrhea and cramping.

What should I do if someone near me is going into anaphylactic shock?

If you are nearby when someone is having an anaphylactic reaction, call 911 or get medical help immediately. The person may need CPR as well.

Other ways to help:

  • Lay the person flat, unless they’re having trouble breathing. In that case, help them sit up to make it easier to breathe.
  • If the person is unconscious, put them on their side. Open up their airway by lifting their chin.

What other anaphylaxis treatments might be necessary in emergencies?

If the person can’t breathe, medical professionals may need to:

  • Place a tube through the nose or mouth into the airway.
  • Perform emergency surgery, called a tracheostomy, to place the tube directly into the trachea (windpipe).

Providers may need to give other treatments for shock, including:

  • IV fluids.
  • IV medication to help the heart and circulatory system.
  • Antihistamines and steroids to reduce symptoms, after they’ve stabilized the person.

Prevention

Can I prevent anaphylaxis?

If you have severe allergies, make sure you carry an epinephrine injection wherever you go.

Take steps to avoid your triggers:

  • Food: Read food labels carefully. Ask restaurants what ingredients are in their dishes and how they prepare them. (Sometimes, restaurants may prepare an allergen-free dish in the same pot or pan as an ingredient you’re allergic to.)
  • Medications: Tell all healthcare providers if you’re allergic to any medications and if you’ve had allergic reactions in the past. They can make sure to prescribe a safe alternative for you and avoid anything you may be allergic to.
  • Insect stings: Don’t walk barefoot in the grass. It’s also smart not to drink from open cans since insects can lurk around the opening. Try to avoid wearing bright, flowery clothing or perfumes, hairsprays and lotions that could attract insects.

What is drug desensitization?

Sometimes, you need to take a medication that you’re allergic to. For example, certain chemotherapy medications to treat ovarian cancer may cause an allergic reaction. There may be no safe alternative.

A healthcare provider, usually an allergist or immunologist, can do drug desensitization. This helps your body temporarily accept the medicine. The provider gives you a very small dose of the medicine. Over a few hours, they gradually increase the dose until you’ve received the full amount. You continue to take the medicine regularly. Doing so keeps you in this temporary non-allergic state. Once you stop taking the medication, you’ll be allergic to it again.

What is venom immunotherapy?

This therapy helps you become less allergic to insect bites. An allergist injects small doses of the venom under your skin. You get a series of these shots, which decrease your sensitivity to the allergen.

What is oral immunotherapy for food allergies?

This therapy tries to desensitize someone to a food allergy by reducing the reaction. You do so under the care of a healthcare provider, usually an allergist. The provider starts by giving you a small dose of the allergen, then slowly increases it over time. The goal is building your tolerance. People who have oral immunotherapy should still carry their epinephrine injector with them. Researchers are investigating how effective this therapy is.

Outlook / Prognosis

What’s the outlook for people who had an anaphylactic reaction?

When people don’t get treatment in time, anaphylaxis may lead to unconsciousness and even death. But if you get prompt treatment with epinephrine, the prognosis is good. You’ll likely make a full recovery.

Living With

How can I best cope with allergies?

If you know you have severe allergies to food or other things, prepare ahead of time:

  • Carry your injector: Have your epinephrine injection kit with you at all times.
  • Have ID: Wear jewelry or carry a card that identifies your allergy. This ID can save your life in emergencies.
  • Don’t wait to inject: Use your epinephrine injection promptly if you come into contact with your allergen.
  • Tell your providers: If you have drug allergies, tell your healthcare provider before any test or treatment. That includes dental care.
  • Educate loved ones: Tell family and friends about the allergy and your triggers. Make sure they know how to recognize anaphylaxis symptoms. Also explain how to use the injector, so they can help you in case of a reaction.

When should I use my epinephrine injector?

If you think you’re having an anaphylactic reaction, don’t wait to use your injector. And don’t take an antihistamine instead to see if that helps. Use your injector immediately. Your life depends on taking quick action. You also need to call 911 or get to a hospital. Even after you inject yourself, you need medical evaluation and treatment.

If you’re not sure you’re having an anaphylactic reaction, it’s better to inject yourself. The risk of an unnecessary injection is less than the risk of not getting the medicine in time.

If you inject yourself without needing to, you may increase your blood pressure and heartbeat for a few hours. Call your provider or get medical help if that happens.

What do I need to do after an epinephrine injection?

Call 911 or find a way to get to the hospital. You need to get to the nearest emergency room if you had an anaphylactic reaction. You need a full evaluation from medical professionals.

When should I see an allergist?

An allergist is a healthcare provider specially trained to diagnose and treat people with allergies. They can help you figure out your triggers, discuss treatment options and help you avoid allergens. Talk to an allergist if you:

  • Have allergy symptoms that are hard to control or manage.
  • Have other medical conditions that make treating allergies more complicated.
  • Need daily allergy medication.
  • Need more tests to figure out what is causing your reactions.
  • Think you may have had an anaphylactic reaction.

If my child has allergies, what should I do?

If your child has allergies, help keep them safe:

  • Educate them about the allergy.
  • Make sure they carry their injector with them and know how to use it.
  • Inform staff at your child’s school of the allergy and share the treatment plan with them.
  • Educate any adults who care for your child about the allergy and how to use the injector.

A note from Cleveland Clinic

Anaphylaxis is when you have a severe allergic reaction to an allergen, such as a certain food or insect bite. Anaphylactic shock can be life-threatening. If you notice anaphylaxis symptoms, inject yourself with epinephrine right away. Then call 911 or get to the emergency room. Prompt anaphylaxis treatment can save your life. Make sure to carry your injector wherever you go. Try to avoid triggers. If you have allergy symptoms that are hard to control or you went into anaphylactic shock, talk to your healthcare provider.

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy