ANAPHYLAXIS

Anaphylaxis is a sudden, potentially life-threatening allergic reaction. The symptoms may begin mildly but quickly become severe, often in a matter of seconds to minutes; occasionally, though, the symptoms develop gradually over a 24-hour period. The more rapidly the symptoms begin, the more severe they generally are. Anaphylaxis may occur again the next time a person is exposed to an allergen (allergy trigger). The first exposure to a trigger generally lays the groundwork for anaphylaxis by creating hypersensitivity. Anaphylaxis should always be considered a medical emergency, and you should seek help right away. It is estimated to be responsible for 500 deaths each year.

Signs and Symptoms

• Itching (often the first symptom), redness, hives, swelling, sweating
• Swelling in the nose or throat, hoarseness, wheezing, difficulty speaking, trouble breathing, chest tightness
• Abnormal heart rate or rhythm, shock, heart attack
• Stomach cramps, nausea, vomiting, diarrhea
• Loss of bladder or bowel control, an urgent feeling of needing to go to the bathroom
• Tingling, headache, light-headedness, feeling disoriented or feeling a sense of doom, fainting, seizures

What Causes It?

Anaphylaxis occurs when the immune system overreacts to an allergen that you have encountered at least once before. Occasionally, through a different mechanism, an anaphylactic-like reaction (called anaphylactoid reaction) occurs with the very first exposure to the allergen. Symptoms are the same for both anaphylaxis and anaphylactoid reactions. Symptoms develop when cells release substances that are meant to protect you against the allergen.

Examples of anaphylaxis triggers include:

• Antibiotics
• Aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs, such as ibuprofen), and prescription opiate pain medications (such as codeine); people with asthma and nasal polyps tend to be at greater risk for an anaphylactoid reaction to these drugs
• Foods, such as nuts, shellfish, egg whites, and berries; those who react to ragweed may also react to chamomile tea
• Insect bites or stings
• Egg-based vaccines
• Ingredients in some allergy skin tests, allergy shots, and vaccines
• Blood transfusions
• Latex (as in condoms, rubber gloves)
• Food coloring and preservatives (such as tartrazine, also known as FDC yellow dye No. 5)
• Although rare, athletes may have an anaphylactoid reaction to exercise after eating certain foods, such as celery, shrimp, apples, squid, wheat, hazelnut, or chicken; this reaction is thought to be related to endorphins

Who's Most At Risk?

The following factors may increase your risk for anaphylaxis:

• Known allergies
• Asthma
• Initial exposure to the allergen by injection (intravenous medication)
• Frequent exposure to the allergen, particularly if frequent exposure is followed by a long delay and then a reexposure
• Taking beta-blockers, angiotensin-converting enzyme (ACE) inhibitors, or angiotensin II receptor blockers (ARBs)—medications used to treat heart disease or high blood pressure