Someone with certain types of allergies (like food allergies) can be at risk for a sudden, potentially life-threatening allergic reaction called . If it happens to you, it can seem scary: You may start out feeling as if you are having a mild allergic reaction, then faint, have trouble breathing, or feel like your throat is closing, for example. But, with the right action, anaphylaxis can be treated.

Anaphylaxis isn't common. But some people with allergies are more at risk than others. People with allergies to insect bites and stings, foods, or certain medications are most at risk for anaphylaxis. So if you have allergies (or a friend or family member does), it's good to know about anaphylaxis and be prepared.

Signs of Anaphylaxis

How can people tell if an allergic reaction is an emergency? One clue is if it happens in two or more of these body systems:

1. skin
2. gastrointestinal system
3. respiratory system
4. cardiovascular system

For example, someone may feel tightness or closing in the throat (respiratory system) together with a fast heartbeat (cardiovascular system).

Here are the most common signs that a person who has been exposed to an allergen might have anaphylaxis:

• difficulty breathing
• tightness in the throat or feeling like the throat or airways are closing
• hoarseness or trouble speaking
• wheezing
• nasal stuffiness or coughing
• nausea, abdominal pain, or vomiting
• fast heartbeat or pulse
• skin itching, tingling, redness, or swelling

What to Do

Anaphylaxis requires immediate treatment. It can get worse very quickly. If you have a known allergy and start to have a reaction, use your epinephrine injector (if you have one), call 911, or immediately go to the nearest emergency room. Let friends know about your allergy so they can help you, if necessary.

What Is Epinephrine?

When someone has anaphylaxis, the body releases allergic chemicals into the blood. These chemicals cause the types of problems mentioned earlier — like a fast heartbeat and trouble speaking.

To work against this reaction, doctors usually want people with life-threatening allergies to carry a medication called epinephrine. Epinephrine works by relieving the symptoms of anaphylaxis. For example, it decreases swelling and raises blood pressure.

Epinephrine has to get into the bloodstream as fast as possible in an emergency. So it needs to be given as an injection. This isn't as scary as it sounds. There's no big needle and plunger involved. Instead, scientists have developed an auto injector about the size of a large pen that's easy to carry and use.

If you need to carry an epinephrine auto injector, your doctor will write you a prescription and show you how to use it.

When to Use Epinephrine

If your doctor prescribes an epinephrine auto injector, carry it with you at all times. With anaphylaxis, seconds count. Epinephrine can be a lifesaver.

If you start to have difficulty breathing, tightness in your throat, feel faint, or if you have allergic symptoms in more than one of the body systems mentioned earlier, give yourself epinephrine right away. Don't try to use your inhaler and wait to see what happens. Go straight for the epinephrine injector! That's especially true if you have food allergies and also have asthma.

After using an epinephrine auto injector, go to a hospital emergency room immediately. Sometimes a person has a second wave of symptoms (called a biphasic reaction). The hospital will observe you for at least 4 hours to be sure you are OK and give you additional treatment, if needed.

Serious allergies can sound scary, but they are treatable. So if you have an auto injector, carry it with you always. That tiny pinprick can mean the difference between life and death!

Reviewed by: Sheelagh M. Stewart, RN, MPH
Date reviewed: February 2012