What is Anaphylaxis?


What is anaphylaxis caused by?

Anaphylaxis is usually caused by a reaction one of the following:

Anyone at risk for anaphylaxis can have a life-threatening allergic reaction – even if previous reactions were mild.
NOTE: Severe reactions can start out with mild symptoms and quickly get worse. Deaths from anaphylaxis have occurred 30 minutes after eating a food allergen and 15 after being stung by a bee.

What are signs and symptoms of anaphylaxis?

Symptoms can be different each time a person experiences anaphylaxis and may vary in severity each time. Once symptoms start, they usually progress quickly.

Symptoms typically involve more than one organ system of the body and can include:

  • Skin: itching, redness, swelling, hives
  • Mouth: itching, swelling of lips, tongue
  • Stomach: vomiting, diarrhea, cramps
  • Respiratory: shortness of breath, wheezing, coughing, chest pain and/or tightness
  • Heart: weak pulse, dizziness, faintness
  • Headache, nasal congestion, watery eyes, sweating
  • Confusion, feeling of impending doom
  • Loss of consciousness

While skin symptoms, such as an itchy rash or hives, are common with anaphylaxis, they do not always occur. Ten to 20% of the time, anaphylaxis will occur with no skin symptoms.

Image of the Infographic "Anaphylaxis at a glance"

What is anaphylactic shock?

Anaphylaxis and anaphylactic shock are terms that are usually used for the same thing. A drop in blood pressure and narrowing of the airways in response to the exposure to an allergen can officially be called anaphylactic shock, while most people refer to it as anaphylaxis. It is treated with epinephrine first, epinephrine fast.

How common is anaphylaxis?

Research shows that it occurs in about 1 in 50 people and some believe the rate is even higher.

Graphic showing life-threatening allergies statistics

What is the treatment for anaphylaxis?

The first line treatment for anaphylaxis is epinephrine. It’s the ONLY medication proven to stop a life-threatening allergic reaction. Epinephrine needs to be given as soon as anaphylaxis symptoms occur.

Any delay in administering epinephrine greatly increases the chance of hospitalization. Delaying or failing to use epinephrine has been associated with fatalities.
photo showing an example of all epinephrine injectors

What is epinephrine?

Epinephrine is a form of adrenaline, a hormone that naturally occurs in the body. It is also used as a life-saving medication to treat anaphylaxis. Epinephrine is given using an auto-injector or injection into the muscle in the outer thigh.

How does epinephrine work?

When epinephrine is given by injection, it increases your heart rate and blood pressure as well as relaxes the muscles in the airways. It reverses swelling and suppresses the body’s immune system’s response to allergens. Epinephrine reverses the symptoms of anaphylactic shock and temporarily halts the allergic reaction.

Epinephrine is the ONLY drug that will reverse anaphylaxis and should be given as soon as symptoms appear.

Any delay in giving epinephrine greatly increases the chance of hospitalization. Deaths due to anaphylaxis are often associated with either delaying the use of epinephrine or not using it at all.

Can antihistamines like Benadryl® help with anaphylaxis?

Antihistamines will not reverse anaphylaxis. Doctors recommend using an epinephrine auto-injector as the first treatment at the sign of any severe allergic reaction. Epinephrine will not harm a patient.

Antihistamines only treat a few minor symptoms of anaphylaxis – like hives. Antihistamines take about 30 or more minutes to take effect, which is far too long to treat an urgent medical condition.

Don’t wait. Don’t delay giving epinephrine. One more time: epinephrine will treat a life-threatening allergic reaction – antihistamines will not.

What if I can’t afford my medication?

Graphic of average time for anaphylactic shock/arrest
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What is a biphasic reaction?

After some people experience an anaphylactic reaction, they will have a secondary, or biphasic reaction. After someone appears to recover from an anaphylactic reaction, a second reaction can occur (without any additional exposure to an allergen) up to 12 hours later or longer. While symptoms are often milder than the initial reaction, they often require a second dose of epinephrine.

It’s important not to leave someone alone following an allergic reaction. This is the main reason why you need to go to the emergency room after using epinephrine.

What to do if you are at risk for anaphylaxis?

People at risk for anaphylaxis should carry two epinephrine auto-injectors at all times. The epinephrine auto-injector needs to be used at the first sign of symptoms and seek follow-up medical care right away. Thirty-percent of people need a second dose of epinephrine to relieve their symptoms.

Studies show that many parents are hesitant to give their child epinephrine. They are often fearful of hurting their child (or themselves) as the primary reason. Sometimes they are uncertain if their child is having a dangerous allergic reaction. Parents need to remember that epinephrine is the life-saving treatment for an allergic reaction and must be given without delay.

What is an Allergy and Anaphylaxis Emergency Plan?

A helpful tool when it comes to managing and treating anaphylaxis, especially in children, is an Allergy and Anaphylaxis Emergency Plan. This is a plan that includes information about a child’s allergy, asthma, and provides an outline of symptoms to watch for and how to give epinephrine. It is an important tool for families, grandparents, caregivers and school staff. Parents should ask their doctor for a completed plan.

For more information on managing anaphylaxis at school, see our publication, “Allergy and Anaphylaxis: A Practical Guide for Schools and Families”.

How do you use an epinephrine injector?

Epinephrine injectors contain a premeasured dose of epinephrine. Two different strengths are available for treating different body weights.

There are several different brands of epinephrine injectors available. Each has its own operating instructions. Be sure to visit the website of the device you are using so you can view the training video and learn how to operate the specific device you have.

Some epinephrine treatments are available as an auto-injector while some are a pre-filled syringe. Be sure you know what your prescribed device is.

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General step-by-step instructions for epinephrine auto-injectors

Epinephrine auto-injectors are easy to use and come with clear instructions. The device’s needle sits protected inside the device until you inject it. Ask your doctor for training on how to correctly use an epinephrine auto-injector; manufacturers’ websites may also provide detailed steps and how-to videos.

  1. Pull off the safety cap or needle covering.
  2. Inject the epinephrine into the outer thigh; avoid the buttocks area. The needle is designed to go through clothing if necessary. Hold the leg and keep it steady while you inject the epinephrine.
  3. Once injected, follow the device’s instructions for how long to keep it in place — usually several seconds — until all the epinephrine is delivered.
  4. Remove the device and massage the injection site for 10 seconds.
  5. Call 911 immediately. Tell the dispatcher you just used epinephrine to treat a suspected anaphylactic reaction. Make arrangements for transport to an emergency department for additional treatment. Side effects may include uncontrollable shaking or twitchiness and feelings of panic or anxiety. These should subside within a few minutes or an hour.

Maintaining Your Epinephrine Injector

Store your epinephrine injectors as close to room temperature as possible. Leaving them in extremely hot or cold temperatures can make the epinephrine ineffective or cause the injector to malfunction. Do not store them in your car or in a refrigerator.

When outside, you need to keep your epinephrine injector close at hand, so pack it in a purse or backpack.

Keep your epinephrine injectors out of direct sunlight; this can cause the epinephrine to oxidize (combine with oxygen, changing the makeup of the drug) and become ineffective. Oxidized epinephrine will appear dark or have solid particles in it. Epinephrine can also oxidize on its own over time, so check your device regularly to be sure the liquid inside is clear.

Epinephrine injectors have an expiration date and they should be replaced as soon as they expire. (However, if all you have is an outdated auto-injector in an emergency, use it as it may provide some benefit.) Check the date on your devices regularly, including backups that may be in a school nurse’s office or at a family member’s house.

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