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Serious Allergic Reactions (Anaphylaxis)

Things to Know About Anaphylaxis

Someone with severe allergies can be at risk for a sudden, potentially life-threatening allergic reaction called anaphylaxis. It can seem scary — a person may faint or feel like his or her 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

As with other allergies, anaphylaxis can trigger symptoms in any of these four body systems:

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

So how can people tell if an allergic reaction is actually an emergency? One clue is if it happens in two or more of these systems — like tightness or closing in the throat together with a fast heartbeat.


  • difficulty breathing
  • hoarseness or trouble speaking
  • wheezing
  • nasal stuffiness or coughing
  • nausea, abdominal pain, or vomiting
  • fast heartbeat or pulse
  • skin itching, tingling, redness, or swelling

Dealing With a Serious Reaction

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

During anaphylaxis, allergic chemicals are released into the blood. These cause the types of symptoms mentioned earlier. 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.

Because epinephrine has to get into the bloodstream as fast as possible in an emergency, it needs to be given in injection form. This isn't as scary as it sounds, though — 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 epinephrine, your doctor will show you how to use it. If you start to have difficulty breathing, tightness in your throat, or feel faint, or if you have allergic symptoms in more than one of the body systems mentioned earlier, it's time to give yourself epinephrine right away. You may want to take over-the-counter (OTC) antihistamines as well — but they won't work alone. OTC antihistamines are never a replacement for epinephrine in life-threatening reactions.

Doctors may recommend that some people use other medications, such as a prescription inhaler, after giving themselves the epinephrine shot.

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). So 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 the good news is they're a lot easier to recognize and treat nowadays than in the past, thanks to greater awareness and the availability of epinephrine.

Reviewed by: Hemant P. Sharma, MD
Date reviewed: January 2008

Kids Health

