Anaphylaxis is a severe, potentially life-threatening allergic reaction. It can occur within seconds or minutes of exposure to something you're allergic to, such as the venom from a bee sting or a peanut.
The flood of chemicals released by your immune system during anaphylaxis can cause you to go into shock; your blood pressure drops suddenly and your airways narrow, blocking normal breathing. Signs and symptoms of anaphylaxis include a rapid, weak pulse, a skin rash, and nausea and vomiting. Common triggers of anaphylaxis include certain foods, some medications, insect venom and latex.
Anaphylaxis requires an immediate trip to the emergency department and an injection of epinephrine. If anaphylaxis isn't treated right away, it can lead to unconsciousness or even death.
Anaphylaxis symptoms usually occur within minutes of exposure to an allergen. Sometimes, however, anaphylaxis can occur a half-hour or longer after exposure. Anaphylaxis symptoms include:
When to see a doctor
If you or your child have had a severe allergy attack or any signs and symptoms of anaphylaxis in the past, make an appointment to see your doctor. The diagnosis and long-term management of anaphylaxis are complicated, so you'll probably need to see a doctor who specializes in allergies and immunology.
Your immune system produces antibodies that defend against foreign substances. This is good when a foreign substance is harmful (such as certain bacteria or viruses). But some people's immune systems overreact to substances that shouldn't cause an allergic reaction. When this occurs, the immune system sets off a chemical chain reaction, leading to allergy symptoms. Normally, allergy symptoms are not life-threatening. But some people have a severe allergic reaction that can lead to anaphylaxis. Even if you or your child have had only a mild allergic reaction in the past, there's still a risk of future anaphylaxis.
A number of allergens can trigger anaphylaxis, depending on what you're allergic to.
Common anaphylaxis triggers include:
Less common causes of anaphylaxis include:
Anaphylaxis triggered by exercise varies from person to person. In some people, aerobic activity, such as jogging, triggers anaphylaxis. In others, less intense physical activity, such as walking, can trigger a reaction. Eating certain foods before exercise or exercising when the weather is hot, cold or humid has also been linked to anaphylaxis in some people. Talk with your doctor about any precautions you should take when exercising.
Anaphylaxis symptoms are sometimes caused by aspirin, other nonsteroidal anti-inflammatory drugs — such as ibuprofen (Advil, Motrin, others) and naproxen sodium (Aleve, Midol Extended Relief) — and the intravenous (IV) contrast used in some X-ray imaging tests. Although similar to allergy-induced anaphylaxis, this type of reaction isn't triggered by allergy antibodies.
If you don't know what triggers your allergy attack, your doctor may do tests to try to identify the offending allergen. In some cases, the cause of anaphylaxis is never identified. This is known as idiopathic anaphylaxis.
There aren't many known risk factors for anaphylaxis, but some things that may increase your risk include:
An anaphylactic reaction can be life-threatening when a severe anaphylactic attack occurs; it can stop breathing or stop your heartbeat. In this case, you'll need cardiopulmonary resuscitation (CPR) and other emergency treatment right away.
Tests and diagnosis
Your doctor will ask you questions about your allergies or any previous allergic reactions you've had. This evaluation will include questions about:
To help confirm the diagnosis:
Your doctor will want to rule out other conditions as a possible cause of your symptoms, including:
Treatments and drugs
During an anaphylactic attack, an emergency medical team may perform cardiopulmonary resuscitation (CPR) if you stop breathing or your heart stops beating. You may be given medications including:
What to do in an emergency
Using an autoinjector
Be sure you know how to use the autoinjector. 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 an epinephrine injection or another medication to treat your symptoms.
Unfortunately, in most other cases there's no way to treat the underlying immune system condition that can lead to anaphylaxis. But you can take steps to prevent a future attack — and be prepared in the event one does occur.
Coping and support
Having a potentially life-threatening reaction is frightening, whether it happens to you or to your child. Developing an anaphylaxis emergency action plan may help put your mind at ease. Work with your or your child's doctor to develop this written step-by-step plan of what to do in the event of a reaction. That way, you'll know exactly what you need to do if anaphylaxis occurs, and you'll have a written plan that you can share with teachers, baby sitters and other caregivers so that they'll know what they need to do, too.
If your child has experienced anaphylaxis, talk to his or her school nurse and teachers to find out what plans they have in place for dealing with an emergency. Make sure school officials have a current autoinjector in case your child needs treatment.
The best way to prevent anaphylaxis is to avoid substances that you know cause this severe reaction. Follow these steps:
Last Updated: 2010-09-03
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