The word allergy means “different action” and was coined by Dr. Clemens von Pirquet in 1905. He maintained that immunity, the body’s response to external stimuli, could be helpful, or, when overblown, had adverse effects. Many infectious diseases, including polio, flu, and tetanus, are controlled by manipulating immune response. But 10 to 30 percent of industrialized populations have allergies, hypersensitive reactions to numerous substances, and this number is increasing.
For allergies to occur, on first meeting a provocative substance (allergen), sensitization occurs and the patient’s immune system says, “I don’t like that.” Subsequent exposures inspire white blood cells to produce immunoglobulins and histamine, chemical messengers that induce mildly unpleasant symptoms such as red, watering eyes; facial flushing; rashes; and itching. Occasionally, however, life-threatening anaphylactic reactions arise, caused by throat swelling that impedes breathing and cardiac problems.
Food allergies cause unpleasant symptoms: pain, diarrhea, vomiting, bloating, wheezing, or swollen lips. Peanut allergy is common, causing some airlines to stop serving small packages of peanuts on their flights—those were the only advantage I ever saw to traveling that way.
Gluten, milk, soy, seafood, and others also can stimulate allergic problems. If eggs affect you, tell health-care providers before any immunization, because eggs are used in vaccine production.
Sulfites are a byproduct of wine and beer production and can be found in many foods such as baked goods, guacamole, and dried fruits. Reactions can be mild or nasty. Lots of drugs cause allergic reactions; antibiotics are common culprits. If you have had an allergic reaction to one antibiotic, tell your doctor prior to taking any antibiotic as crossover allergies can occur.
Hay fever, a seasonal allergy, is common and mild, usually presenting with itchy watering eyes, sneezing, and scratchy throat. It can provoke asthma attacks, so folks with that condition should be more careful about exposure to allergens—listen to pollen reports and avoid certain environments. Some people are sensitive to fungi and various molds. Other allergies include those to poison ivy, oak, or sumac, or to cats and dogs.
Skin is our largest organ, a set-up for exposure to environmental chemicals that may cause allergy. For instance, latex in domestic (and surgical) gloves, sunscreen, deodorants, or make-up all can cause problems. Bee, wasp, or yellow jacket stings can mimic an electric shock, but allergic responses can occur and cause anaphylactic shock.
If allergies are suspected, testing protocols involve exposing skin to a small amount of the potential allergen and if local swelling, pain, or irritation occurs, the cause is apparent; one can also look for elevated immunoglobulin levels in blood.
Avoiding allergens is ideal, but if symptomatic contact occurs, antihistamine treatment squashes histamine-induced effects. Steroids, delivered locally to the site of problems, may also help. For instance, allergic rhinitis is addressed by squirting meds up the nostril. Eye drops, creams, tablets, and intravenous steroids are available. For anaphylaxis, epinephrine injections can assist and people who are at risk keep epi pens with them. Efforts to desensitize allergic patients by gradually exposing them to increasing doses of allergens may work in certain cases.
Why are some people allergic? There is no clear answer, but there does seem to be a familial element—twins tend to have similar allergies. There is also the “hygiene hypothesis”—kids from larger families tend to have fewer allergies, potentially because it is harder to keep everyone clean, so persistent exposure to many irritants does not lead to allergy. As for flying? Don’t fly if in the middle of an attack and certainly do not fly if taking antihistamines. Discuss your condition with your physician or AME and put safety first.
Dr. Jonathan Sackier is a medical advisor for the AOPA Pilot Protection Services program and an active general aviation pilot.
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