|SSM Cardinal Glennon Children's Medical Center|
All About Allergies
Dust, cats, peanuts, cockroaches. An odd grouping, but one with a common thread: allergies — a major cause of illness in the United States. Up to 50 million Americans, including millions of kids, have some type of allergy. In fact, allergies account for the loss of an estimated 2 million schooldays per year.
An allergy is an overreaction of the immune system to a substance that's harmless to most people. But in someone with an allergy, the body's immune system treats the substance (called an allergen) as an invader and reacts inappropriately, resulting in symptoms that can be anywhere from annoying to possibly harmful to the person.
In an attempt to protect the body, the immune system of the allergic person produces antibodies called immunoglobulin E (IgE). Those antibodies then cause mast cells and basophils (allergy cells in the body) to release chemicals, including histamine, into the bloodstream to defend against the allergen "invader."
It's the release of these chemicals that causes allergic reactions, affecting a person's eyes, nose, throat, lungs, skin, or gastrointestinal tract as the body attempts to rid itself of the invading allergen. Future exposure to that same allergen (things like nuts or pollen that you can be allergic to) will trigger this allergic response again. This means every time the person eats that particular food or is exposed to that particular allergen, he or she will have an allergic reaction.
Who Gets Allergies?
The tendency to develop allergies is often hereditary, which means it can be passed down through your genes. However, just because you, your partner, or one of your children might have allergies doesn't mean that all of your kids will definitely get them, too. And someone usually doesn't inherit a particular allergy, just the likelihood of having allergies.
But a few kids have allergies even if no family member is allergic. A child who is allergic to one substance is likely to be allergic to others as well.
Common Airborne Allergens
Some of the most common things people are allergic to are airborne (carried through the air):
Common Food Allergens
The American Academy of Allergy, Asthma, and Immunology estimates that up to 2 million, or 8%, of kids in the United States are affected by food allergies, and that eight foods account for most of those food allergy reactions in kids: eggs, fish, milk, peanuts, shellfish, soy, tree nuts, and wheat.
Other Common Allergens
Some kids also have what are called cross-reactions. For example, kids who are allergic to birch pollen might have reactions when they eat an apple because that apple is made up of a protein similar to one in the pollen. Another example is that kids who are allergic to latex (as in gloves or certain types of hospital equipment) are more likely to be allergic to kiwifruit, water chestnuts, or bananas.
Signs and Symptoms
The type and severity of allergy symptoms vary from allergy to allergy and child to child. Allergies may show up as itchy eyes or an itchy nose, sneezing, nasal congestion, throat tightness, trouble breathing, and even shock (faintness or passing out).
Symptoms can range from minor or major seasonal annoyances (for example, from pollen or certain molds) to year-round problems (from allergens like dust mites or food). Allergies to dust mites are common to the eastern parts of the United States, but not in areas of high-altitude and low humidity (for example, like Colorado).
Because different allergens are more prevalent in different parts of the country and the world, allergy symptoms can also vary, depending on where you live. For example, peanut allergy is unknown in Scandinavia, where they don't eat peanuts, but is common in the United States, where peanuts are not only a popular food, but are also found in many of the things we eat.
Airborne Allergy Symptoms
Airborne allergens can cause something known as allergic rhinitis, which occurs in about 15% to 20% of Americans. It develops by 10 years of age and reaches its peak in the early twenties, with symptoms often disappearing between the ages of 40 and 60.
Symptoms can include:
These symptoms are often accompanied by itchy, watery, and/or red eyes, which is called allergic conjunctivitis. (When dark circles are present around the eyes, they're called allergic "shiners.") Those who react to airborne allergens usually have allergic rhinitis and/or allergic conjunctivitis. If a person has wheezing and shortness of breath, the allergy may have progressed to become asthma.
Food Allergy Symptoms
The severity of food allergy symptoms and when they develop depends on:
Symptoms of food allergies can include:
Insect Venom Allergy Symptoms
Being stung by an insect that a child is allergic to may cause some of these symptoms:
In rare instances, if the sensitivity to an allergen is extreme, a child may experience anaphylaxis (or anaphylactic shock) — a sudden, severe allergic reaction involving various systems in the body (such as the skin, respiratory tract, gastrointestinal tract, and cardiovascular system).
Severe symptoms or reactions to any allergen, from certain foods to insect bites, require immediate medical attention and can include:
Anaphylaxis can happen just seconds after being exposed to a triggering substance or can be delayed for up to 2 hours if the reaction is from a food. It can involve various areas of the body.
Fortunately, though, severe or life-threatening allergies occur in only a small group of kids. In fact, the annual incidence of anaphylactic reactions is small — about 30 per 100,000 people — although those with asthma, eczema, or hay fever are at greater risk of experiencing them. Most anaphylactic reactions — up to 80% — are caused by peanuts or tree nuts.
Some allergies are fairly easy to identify because the pattern of symptoms following exposure to certain allergens can be hard to miss. But other allergies are less obvious because they can masquerade as other conditions.
If your child has cold-like symptoms lasting longer than a week or two or develops a "cold" at the same time every year, consult your doctor, who will likely ask questions about the symptoms and when they appear. Based on the answers to these questions and a physical exam, the doctor may be able to make a diagnosis and prescribe medications or may refer you to an allergist for allergy skin tests and more extensive therapy.
To determine the cause of an allergy, allergists usually perform skin tests for the most common environmental and food allergens. These tests can be done in infants, but they're more reliable in kids over 2 years old.
A skin test can work in one of two ways:
If reactions to a food or other allergen are severe, a blood test may be used to diagnose the allergy so as to avoid exposure to the offending allergen. Skin tests are less expensive and more sensitive than blood tests for allergies. But blood tests may be required in children with skin conditions or those who are extremely sensitive to a particular allergen.
Even if a skin test and/or a blood test shows an allergy, a child must also have symptoms to be definitively diagnosed with an allergy. For example, a toddler who has a positive test for dust mites and sneezes frequently while playing on the floor would be considered allergic to dust mites.
There is no real cure for allergies, but it is possible to relieve symptoms. The only real way to cope with them is to reduce or eliminate exposure to allergens. That means that parents must educate their kids early and often, not only about the allergy itself, but also about what reaction they will have if they consume or come into contact with the allergen.
Informing any and all caregivers (childcare personnel, teachers, extended family members, parents of your child's friends, etc.) about your child's allergy is equally important.
If reducing exposure isn't possible or is ineffective, medications may be prescribed, including antihistamines (which you can also buy over the counter) and inhaled or nasal spray steroids.
In some cases, an allergist may recommend immunotherapy (allergy shots) to help desensitize your child. However, allergy shots are only helpful for allergens such as dust, mold, pollens, animals, and insect stings. They're not used for food allergies, and someone with food allergies must avoid that food.
Here are some things that can help kids avoid airborne allergens:
Food allergies usually aren't lifelong (although those to peanuts, tree nuts, and seafood can be). Avoiding the food is the only way to avoid symptoms while the sensitivity persists.
Doctors often recommend that caregivers of kids who are extremely sensitive to a particular food, have asthma in addition to the food allergy, or are allergic to insect venom carry injectable epinephrine (adrenaline) to counteract any allergic reactions.
Available in an easy-to-carry container that looks like a pen, injectable epinephrine is carried by millions of parents (and older kids) everywhere they go. With one injection into the thigh, the device administers epinephrine to ease the allergic reaction.
An injectable epinephrine prescription usually includes two auto-injectors and a "trainer" that contains no needle or epinephrine, but allows you and your child (if he or she is old enough) to practice using the device. It's vital that you familiarize yourself with the procedure by practicing with the trainer. Your doctor also can provide instructions on how to use and store injectable epinephrine.
Make sure kids 12 years or older keep injectable epinephrine readily available at all times. If your child is younger than 12, talk to the school nurse, teachers, and your childcare provider about keeping injectable epinephrine on hand in case of an emergency.
It's also important to ensure that injectable epinephrine devices are available in your home and in the homes of friends and family members if your child spends time there. Your doctor may also encourage your child to wear a medical alert bracelet. It's also wise to carry an over-the-counter antihistamine, which can help alleviate allergy symptoms in some people. But antihistamines should not be used as a replacement for the epinephrine pen.
Kids who have had to take injectable epinephrine should go immediately to a medical facility or hospital emergency department, where additional treatment can be given if needed. Up to one third of anaphylactic reactions can have a second wave of symptoms several hours following the initial attack, so these kids might need to be observed in a clinic or hospital for 4 to 8 hours following the reaction even though they seem well.
The good news is that only a very small group of kids will experience severe or life-threatening allergies. With proper diagnosis, preventive measures, and treatment, most kids can keep their allergies in check and live happy, healthy lives.
Reviewed by: William J. Geimeier, MD