What Is Anaphylaxis?

Anaphylaxis is a rare but severe allergic reaction. It occurs suddenly, can worsen quickly and can be deadly. Anaphylaxis happens after being exposed to a triggering agent. The agent leads to the release of normal body chemicals such as histamine that cause allergy symptoms.

What Are the Symptoms of Anaphylaxis?

The symptoms of anaphylaxis can be quite different from one person to the next. The early symptoms may be mild: a runny nose, a skin rash or a "strange feeling." These symptoms can quickly become more serious:

  • Trouble breathing
  • Hives or swellings
  • Tightness of the throat
  • Hoarse voice
  • Nausea
  • Vomiting
  • Abdominal pain
  • Diarrhea
  • Dizziness
  • Low blood pressure
  • Rapid heart beat
  • Feeling of doom
  • Cardiac arrest

What Is the Emergency Treatment of Anaphylaxis?

An epinephrine (adrenalin) shot is the most common emergency treatment for anaphylaxis. Epinephrine helps keep blood pressure normal. It also helps make breathing easier. Epinephrine works best when it is injected immediately after the problem starts.

Symptoms usually improve quickly after epinephrine is injected. Epinephrine works fast, but the effects do not last very long. The doctor or nurse may give you a second and third dose of epinephrine.

Sometimes other medicine such as prednisone and an antihistamine are given as part of the treatment. These other medicines can not stop an anaphylactic attack, but they help treat some of the symptoms such as itching and swelling.

You may get a prescription for an easy-to-use, self-treatment shot of epinephrine. You should carry this shot with you at all times for emergency self-treatment of an unexpected anaphylaxis attack. Have someone show you how to use this shot correctly. Read the information that comes with the shot. Always get emergency medical care immediately after using a self-treatment shot of epinephrine because one shot may not be enough to stop an attack.

What Starts (Triggers) These Severe Allergic Reactions?

The most common triggers are: medicines, foods, insect stings and latex. Less common triggers include X-ray dyes and exercise.

Medicines: The allergy attack can start slowly or quickly. The most severe attacks happen when the medicine enters the body as a shot or through an IV.

Penicillin and related antibiotics are the most common medicines that cause anaphylaxis. Many other medicines also can cause anaphylaxis. A very similar problem can happen after taking aspirin or a related medicine such as ibuprofen. To prevent trouble in the future, tell your doctors, nurses, pharmacists and dentists about your medicine allergies.

Foods: Peanuts, tree nuts, fish, shellfish, milk and eggs are the most common food triggers. The symptoms usually start shortly after eating the problem food. In very allergic people, even one taste of the food can cause a reaction.

The best way to prevent trouble is to avoid eating the trigger food. When shopping for food, check ingredient labels carefully. When eating at a restaurant, check all foods with the chef before eating. If you child has a food allergy, make sure his or her school is prepared. The school should have an emergency plan and a shot of epinephrine in case of an unexpected food allergy attack.

Insect stings: Insects known to trigger anaphylaxis include:

  • Honeybees
  • Yellow jackets
  • Hornets
  • Wasps
  • Fire Ants

In highly allergic people, even one sting can be life-threatening. You can help prevent the chances of a future attack:

  • Do not use perfume or cologne
  • Do not wear brightly colored clothing
  • Get treatment (insect sting allergy shots) from an allergist

The allergy shots (immunotherapy) involve injections of insect venom in gradually increasing amounts for 3 or more years. During and after treatment, you should still avoid new insect stings.

Latex: Allergy to latex has become more common in recent years. Latex allergy usually is caused by natural rubber latex, not by synthetic latex.

Products containing natural rubber latex include:

  • Disposable gloves
  • IV tubes
  • Airway tubes
  • Syringes
  • Stethoscopes
  • Adhesive tapes
  • Catheters

Children with spina bifida and healthcare workers are at a higher risk for latex allergy.

Before any medical or dental work, tell your doctor or dentist about your latex allergy. Request that all tests and treatments be done in an environment which is latex-free.

X-Ray Dyes: Theses test agents can cause a reaction that is just like anaphylaxis. Fortunately, there are new types of X-ray dyes that rarely cause this problem.

Exercise: Physical activity can cause allergic symptoms in some people. Rarely, this can lead to anaphylaxis. In some cases, it is triggered by eating certain foods before exercise. Most symptoms can be controlled by medicines and by stopping exercise when symptoms start.

How Can I Pinpoint My Anaphylactic Trigger?

Any substance or food you had contact with just before the start of the anaphylaxis attack is a possible trigger. Make a very detailed list, and take this list with you when you see your doctor. Many times an allergist can help you find the trigger of your anaphylaxis attack. Testing may include skin tests and/or blood tests.

What Is Idiopathic Anaphylaxis?

Sometimes, doctors cannot pinpoint the cause of your attack. When a specific trigger cannot be found, the trouble is said to be "idiopathic," which means "without known cause."

What should I do if I had anaphylaxis in the past?

  • If you had an anaphylaxis attack in the past:
  • Wear a medical bracelet that lists your trigger.
  • Avoid your trigger. The most effective way to prevent future trouble is to avoid contact with your trigger.
  • Know what to do if you unexpectedly come into contact with your trigger. Your doctor can help you make a detailed plan for emergency care.
  • If your doctor has prescribed an epinephrine shot, carry it with you at all times.
  • Teach your family and friends how to help you if you begin to have anaphylaxis and cannot help yourself.

Reviewed and Updated: July 2008
© American College of Allergy, Asthma and Immunology