Anaphylaxis

Overview

Anaphylaxis is a severe and potentially life-threatening allergic reaction to such allergy-causing substances as insect venoms, latex, foods and medications.

Your immune system produces antibodies that defend against foreign substances, including allergens. These antibodies release chemicals that may cause symptoms such as watery eyes and a runny nose. Anaphylaxis occurs when your immune system severely overreacts to an allergen.

Allergy Relief

Some of the medications used to treat respiratory allergy symptoms include antihistamines, decongestants, nasal sprays and eyedrops. What do medications do? Allegra D Allegra Claritin-D Flonase Nasacort Nasacort AQ Nasonex Patanol Zyrtec

The flood of chemicals in your body makes your blood pressure drop suddenly, and your bronchial tubes narrow, causing difficulty breathing or even unconsciousness and death. You may have an anaphylactic response within seconds or minutes of exposure to an allergen such as a bee sting or an ingested peanut.

Although anaphylaxis is the most dangerous type of allergic reaction, it’s also the least common. Still, hundreds of Americans die of anaphylactic shock each year.

Fortunately, you can be prepared to respond quickly and effectively to an allergic emergency. It’s equally important to do all you can to prevent exposure to life-threatening allergens.

Signs and symptoms

An anaphylactic reaction is most likely to occur after you’ve been stung by a bee or bitten by an insect, eaten food containing food allergens, or taken a new medication. The effects of anaphylaxis aren’t limited to the site of the exposure. Suspect anaphylaxis if you develop the following signs and symptoms within minutes of exposure to an allergen:

• Constriction of your airways, including a swollen throat, that results in difficulty breathing
  
• Shock associated with a severe decrease in blood pressure
  
• Weak and rapid pulse
  
• Dizziness or fainting
  
• Hives and large welts below your skin surface (angioedema)
  
• Flushing of your skin and intense itching
  
• Swelling of your lips and tongue
  
• Nausea, vomiting or diarrhea

Causes

Many allergens can cause anaphylaxis. Sometimes the cause of an anaphylactic reaction is unknown. Common causes of anaphylaxis include:

• Drugs such as penicillin
  
• Foods such as peanuts, tree nuts (walnuts, pecans), fish and shellfish
  
• Insect bites and stings from bees, yellow jackets, wasps, hornets and fire ants
  
• Latex

Pollens, molds and dust mites rarely cause an anaphylactic response.

Risk factors

Anaphylaxis isn’t a common condition. However, if you have a history of allergies or asthma, you may be at increased risk — especially if you’ve had prior anaphylactic reactions. Future reactions may be more severe than the first.

Screening and diagnosis

See a specialist in allergies and immunology if you’ve experienced an episode of anaphylaxis or think you’ve experienced some of the signs and symptoms associated with it. An evaluation typically includes questions about:

• Food
  
• Medications
  
• Latex
  
• Insect stings

You may be tested for allergies with skin tests or blood tests. The specialist can provide you instructions on how you might prevent future anaphylactic reactions and how to self-administer medication if you do have a reaction. You may also be asked to keep a detailed list of what you eat or to stop eating certain foods for a time.

Treatment

Adrenaline (epinephrine) is the drug most commonly used to treat anaphylactic reactions. It can be self-administered with an autoinjector, a combined syringe and concealed needle that injects a single dose of medication when pressed against your thigh. Your doctor may recommend that you carry epinephrine and show you how to use the autoinjector. 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 response to a severe anaphylactic reaction also may give you epinephrine.

A doctor or emergency medical team may perform Cardiopulmonary resuscitation (CPR). They may also inject you with antihistamines and cortisone to reduce inflammation of your air passages and improve your breathing.

If you’re with someone who has experienced anaphylaxis and shows signs of shock — pale, cool, and clammy skin, weak and rapid pulse, shallow breathing, dilated pupils, weakness, confusion, anxiety — follow these steps:

• Call 911 or emergency medical help immediately.
  
• Check to see if the person is carrying special medications to treat an allergic attack.
  
• Get the person to lie down on his or her back and elevate the feet higher than the head. Keep him or her from moving unnecessarily.
  
• Keep the person warm and comfortable. Loosen tight clothing and cover him or her with a blanket. Don’t give the person anything to drink.
  
• If the person is vomiting or bleeding from the mouth, place the person on his or her side to prevent choking.

Antihistamines: One form of allergy relief

Prevention

The best way to prevent anaphylaxis is to avoid substances that you know cause this severe reaction. Follow these steps to help ensure your well-being:

• Wear a medical alert necklace or bracelet to indicate if you have an allergy to specific drugs or other substances.
  
• Alert your doctor to your drug allergies before having any medical treatment. If you receive allergy shots, always wait at least 30 minutes before leaving the clinic so that you can receive immediate treatment if you have a severe reaction.
  
• Keep a properly stocked emergency kit with prescribed medications available at all times. Your physician can advise you on the appropriate contents. This may include an epinephrine autoinjector.
  
• If you’re allergic to stinging insects, exercise caution when they’re nearby. Wear long-sleeved shirts and trousers. Avoid bright colors and don’t wear perfumes or colognes. Stay calm if you come in close proximity to a stinging insect. Move away slowly and avoid slapping at the insect.
  
• Avoid wearing sandals or walking barefoot in the grass if you’re allergic to insect stings.
  
• Read food labels and ask about ingredients in foods served in restaurants.

Provided by ArmMed Media
Revision date: July 4, 2011
Last revised: by Dave R. Roger, M.D.

RELATED STORIES:
Epinephrine: Treatment for anaphylaxis   Allergy treatments   Hives and angioedema   Allergy definitions   Hay fever   Antihistamines: One form of allergy relief   Food allergy   Decongestants: One way to relieve allergy symptoms

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