Anaphylaxis: First aid

A severe allergic reaction (anaphylaxis) can produce shock and life-threatening respiratory distress. In sensitive people, anaphylaxis can occur within minutes or up to several hours after exposure to a specific allergy-causing substance. Almost any allergy-causing substance — including insect venom, pollen, latex, certain foods and drugs — can cause anaphylaxis. Some people have anaphylactic reactions from unknown causes.

If you're extremely sensitive, you might break out in hives, and your eyes or lips might swell severely. The inside of your throat might swell as well, even to the point of causing difficulty breathing and shock. Dizziness, mental confusion, abdominal cramping, nausea, vomiting or diarrhea also may accompany anaphylaxis.

If you've had an anaphylactic reaction in the past, carry medications with you as an antidote. Epinephrine is the most commonly used drug for severe allergic reactions. It comes only as an injection that must be prescribed by your doctor. You should also carry an antihistamine pill, such as diphenhydramine (Benadryl, others), because the effects of epinephrine are only temporary. Seek emergency medical attention immediately after taking these medications.

If you observe someone having an allergic reaction with signs of anaphylaxis:

1. Call 911 or your local medical emergency number.
2. Check for special medications that the person might be carrying to treat an allergic attack, such as an auto-injector of epinephrine (for example, EpiPen). Administer the drug as directed — usually by pressing the auto-injector against the person's thigh and holding it in place for several seconds. Massage the injection site for 10 seconds to enhance absorption. If your doctor prescribed an auto-injector of epinephrine, read the instructions before a problem develops and also have your household members read them. After administering epinephrine, have the person take an antihistamine pill if he or she is able to do so without choking.
3. Have the person lie still on his or her back with feet higher than the head.
4. Loosen tight clothing and cover the person with a blanket. Don't give anything to drink.
5. If there's vomiting or bleeding from the mouth, turn the person on his or her side to prevent choking.
6. If there are no signs of circulation (breathing, coughing or movement), begin CPR.