Anaphylaxis (Anaphyactic Shock)

Anaphylaxis is a severe and potentially life-threatening allergic reaction. It is also referred to as an anaphylactic reaction or anaphylactic shock.

Anaphylaxis occurs when your immune system has a severe reaction to an allergen. The reaction can lead to a sudden drop in blood pressure (hypotension) and restriction of the airways. These events can result in difficulty breathing, unconsciousness and, rarely, death.

You can be prepared to respond to anaphylaxis by knowing its signs and symptoms, and by carrying emergency medication with you, such as injectable epinephrine (Epipen®).

It's also important to do everything you can to prevent exposure to the allergens that you have identified as triggers for your allergic reaction.

Causes of anaphylaxis

Any substance that can trigger an allergic reaction can also cause anaphlaxis. Allergens that are known to be common triggers of anaphylaxis include the following:

  • Foods, such as peanuts, walnuts, pecans, milk, eggs, fish or shellfish
  • Medications, such as penicillin
  • Insect venoms, such as bees or wasps
  • Latex

Signs and symptoms of anaphylaxis

The signs of anaphylaxis occur within minutes or seconds after being exposed to an allergen.

The following signs and symptoms are a strong indication of anaphylaxis:

  • Constriction of the airways (wheezing) and a swollen tongue or throat, that results in difficulty breathing
  • A drop in blood pressure resulting in dizziness, fainting or shock.
  • A weak and rapid pulse
  • Hives and widespread itching
  • Flushed or pale skin
  • Nausea, vomiting or diarrhea

Risk factors for anaphylaxis

Most people with allergies never experience an anaphylactic reaction. However, having an allergy puts a person at risk of develop anaphylaxis.

If you have had an anaphylactic reaction before, you are at greater risk of having another reaction in the future. Anaphylactic reactions can also grow increasingly severe with each episode.

Screening and diagnosis

It is very important that you see your doctor if you have experienced an episode of anaphylaxis or think you've experienced some of the signs and symptoms associated with it.

Allergy tests may be performed to determine what might have lead to anaphylaxis.

Treatment of anaphylaxis

There is no medication that will prevent someone from developing anaphylaxis. However, there are medications that control the reaction once it starts.

Epinephrine (adrenaline) is the drug most commonly used to treat anaphylactic reactions once they start. It must be injected into the muscle to be effective. To help patients and/or family members administer the injection, epinephrine is made available as a self-injectable unit, or auto-injector. Brand names of self-injectable epinephrine include, EpiPen, EpiPen Jr. and Twinject.

An auto-injector is a combined syringe and concealed needle that injects a single dose of medication when pressed against your thigh. Your doctor may recommend that you carry an epinephrine auto-injector with you at all times, including school and work.

Be sure you know how to use the auto-injector properly. Also, make sure the people closest to you know how to administer the drug — if they're with you in an anaphylactic emergency, they could save your life. Medical personnel called in to respond to a severe anaphylactic reaction also may give you epinephrine.

If necessary, a doctor or emergency medical team may perform cardiopulmonary resuscitation (CPR). They may also administer intravenous antihistamines and cortisone to reduce inflammation of your air passages and improve your breathing.

If you're with someone who has experienced anaphylaxis and shows signs of shock — pale, cool and clammy skin, weak and rapid pulse, shallow breathing, confusion, anxiety — follow these steps:

  • Call 911 or emergency medical help immediately.
  • Check to see if the person is carrying special medications to treat an allergy attack. If so, administer the medication.
  • Get the person to lie down on his or her back. Elevate the feet higher than the head to keep adequate blood flow to the brain, which will prevent fainting. Keep him or her from moving unnecessarily.
  • Keep the person warm and comfortable. Loosen tight clothing and cover him or her with a blanket. Don't give the person anything to drink.
  • If the person is vomiting or bleeding from the mouth, place the person on his or her side to prevent choking.

If the person isn't breathing or has no pulse, perform CPR.

Anaphylaxis prevention

The best way to prevent anaphylaxis is to avoid substances that you know cause this severe reaction. Follow these steps to help ensure your well-being:

  • Wear a medical alert necklace or bracelet to indicate if you have an allergy to specific drugs or other substances.
  • Keep a properly stocked emergency kit with prescribed medications available at all times. This may include an epinephrine autoinjector.
  • Make sure your epinephrine autoinjector has not expired. These medications generally last 18 months.
  • Alert your doctor to your drug allergies before having any medical treatment. If you receive allergy shots, always wait at least 30 minutes before leaving the clinic so that you can receive immediate treatment if you have a severe reaction to the allergy shot.
  • If you are allergic to stinging insects, exercise caution when they're nearby. Wear long-sleeved shirts and trousers. Avoid bright colors and don't wear perfumes or colognes. Stay calm if you come in proximity to a stinging insect. Move away slowly and avoid slapping at the insect. Avoid wearing sandals or walking barefoot in the grass if you're allergic to insect stings.
  • If you have food allergies, read the labels of all the foods you buy. Manufacturing processes can change, so it's important to periodically recheck the labels of foods you commonly eat. When eating out, ask about ingredients in the food, and ask about food preparation because even small amounts of the food you're allergic to can cause a serious reaction.

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Last updated: 5/13/2022