Division of Pediatric Allergy & Immunology: Frequently Asked Questions

What is allergy skin testing?
Your physician may use allergy testing along with a history and physical exam to confirm or exclude allergies as a cause of certain medical conditions (food reactions, nasal symptoms, eczema, asthma, etc). During allergy skin testing, the skin is pricked with a specially designed skin test device with a drop of allergen on the end of the device. The results are read 15-20 minutes after the application of the allergen to the skin. If you are allergic, you will develop a small red itchy bump on the area of testing which usually resolves in minutes.

Allergy skin testing is useful in certain medical conditions including asthma, hay fever, food allergies, eczema or atopic dermatitis, or stinging insect allergies such as bee sting allergies. Your doctor can determine if you need allergy skin testing from your medical history and exam. And based on the information provided by your skin testing results and presentation, your doctor can provide a medical plan including avoidance strategies and medications.

How young can my child be skin tested for allergies?
Skin prick testing for allergies can be performed at any age, even in young infants if necessary. However, skin testing is not recommended before an individual shows symptoms because an accurate diagnosis depends on an individual's medical history. The medical history is important in determining which factors could be causing an allergic reaction. Skin tests are the most accurate method for confirming an allergy. The skin is pricked with a minute amount of allergen extract to determine if an individual makes allergic antibodies, IgE, against that allergen. Results are typically available with 15-20 minutes.

What role does heredity play in developing allergies?
Allergies have a strong genetic component. If only one parent has allergies (environmental, food, insect sting, etc), each child has a 1 in 3 chance of developing allergies. However, children are much more likely to have allergies if both parents are allergic. With two allergic parents, each child has a 7 in 10 chance of developing allergies. Even though children may be born with a predisposition to develop allergies, they do not necessarily develop the same allergies as their parents. The development of specific allergies depends upon the genes inherited from parents, exposure to specific allergens, and the timing, intensity, and length of exposure to an allergen.

Heredity does not play a role in some types of allergy however, such as contact dermatitis. An example of contact dermatitis is poison ivy allergy. An individual must be exposed to the oil from the plant before he or she can develop the allergy. The first exposure may sensitize an individual to poison ivy. Upon re-exposure to poison ivy, a contact dermatitis rash may appear in areas of contact with the plant. Metals such as nickel, dyes, and other chemicals can also cause contact dermatitis.

Why are food allergies on the rise in children?
Food allergies affect about 6-8% of infants and young children up to 5 years of age. The most common food allergies are cow's milk, egg, wheat, soy, fish, shellfish, peanut and tree nut (almond, walnut, pecan, hazelnut, cashew, pistachio, etc) in pediatric patients. In adults, peanut, tree nut, fish and shellfish are common. In 1997, a random analysis survey by telephone revealed .4% prevalence of peanut allergy in American children which increased to 0.8% in 2002.

There are a number of theories why food allergies are increasing however, definitive scientific data is lacking. Several hypotheses exist but the number one to be considered is the increased awareness of food allergies. In addition, a significant number of patients have food intolerances which they mistakenly label as a food allergy. For example, in lactose intolerance, individuals have an inability to digest milk sugar lactose due to the lack of an enzyme, lactase, in the gut.

Some scientists suspect that some of the following may be responsible for the increase in food allergy. These theories include hygiene, dietary fat, antioxidants, vitamin D and exposure to allergens both orally and topically through the skin. Scientists continue to evaluate these hypotheses and others.

The theories are as follows:

  • Hygiene Hypothesis: better hygiene with less microbial exposure may lead to an increase in atopic disease.
  • Dietary Fat Hypothesis: Decreased consumption of omega-3 fatty acids and increased consumption of vegetable oils may lead to increased IgE (allergic antibody) production.
  • Antioxidant Hypothesis: Dietary changes that have led to increased consumption of processed foods and less fresh produce may lead to increase susceptibility to allergy due to decrease intake of antioxidants, such as vitamin C and beta carotene, which have protective anti-inflammatory effects.
  • Vitamin D hypothesis: Proposed but unproven theories have suggested that both vitamin D excess and deficiency may play a role.
  • Dual Allergen Exposure: Sensitization likely to occur in young children via low dose food by the cutaneous route rather then high dose by oral route.
  • Food Processing: Example, in countries where peanuts are boiled (China, Africa) rather then roasted there is a lower incidence of peanut allergy. It is thought that certain food processing methods may alter the proteins in such a way that may make them more likely to promote an allergic response.

What are the signs my child is developing a food allergy?
True food allergies are caused by an allergic reaction to specific food(s). This allergic reaction involves IgE, which is the allergic antibody. Food reactions that do not involve IgE are called food intolerances.

Food allergies are caused when a specific food is eaten to which someone has produced IgE antibodies. These antibodies interact with cells in the body that release histamine and other allergic chemicals, producing symptoms.

These symptoms commonly involve the skin, gastrointestinal, and respiratory systems. Skin may show hives, flushing or redness, swelling and itching. Breathing problems may include shortness of breath, wheezing, coughing and throat closing. Nausea, vomiting, cramping and diarrhea may occur in the gastrointestinal tract. Other symptoms include dizziness and passing out.

A food allergy will typically occur within 30 minutes or less and almost always within 2 hours of eating. Food allergy can occur with almost any food, but those foods most likely to cause an allergic reaction in children are peanuts, milk, egg, soy and wheat. If you are concerned that your child may be allergic to food(s), an allergist/immunologist will help to diagnose the allergy or other causes of symptoms and recommend appropriate treatment for this potentially life-threatening condition.

What is the difference between food intolerance and a food allergy?
A food allergy is an immune system response. Food intolerance involves other systems. Food allergy happens when the body mistakes a particular food item, classically a protein, for an invading parasite. The most common food allergies are peanuts, tree nuts (such as walnuts, cashews, pecans, and almonds), fish, and shellfish, milk, eggs, soy, and wheat.

When your body decides to rebel against a suspect food, it produces allergic antibodies to it. Now it is armed and ready when it next encounters that same food. The next time you eat any amount of that food, the antibodies sense it and alert your immune system. Your immune system then releases histamine and other chemicals locally and into your bloodstream, leading to food allergy symptoms.

Within minutes you may experience hives, swelling, nausea, vomiting and diarrhea, bloating and stomach pain, shortness of breath, wheezing, swelling of the airways to the lungs, and full blown anaphylaxis, and possibly even death.

Food intolerance typically does not involve the immune system. A lot of different causes can trigger symptoms. A classic example is lactose intolerance which can cause bloating, cramping, diarrhea and excess gas. Lactose intolerance is due to lack of an enzyme needed to fully digest lactose, milk sugar.

Another example would be food sensitivities to additives such as sulfites used to preserve dried fruit, canned goods and wine. In some people sulfites can trigger an asthma attack.

Food allergies can be triggered by even a small amount of the food and occur every time the food is ingested. People with food allergies are generally advised to avoid the offending foods completely. On the other hand, food intolerances often are dose related.
The best way to determine whether you have a true allergy or not is to be evaluated by an allergist who may have you keep a food diary, try an elimination diet, or test by skin prick or blood sample.

My child is allergic to peanuts. Can he eat food processed in the same facility or on the same machinery as peanuts?
No. A study published in the Journal of Allergy and Clinical Immunology in 2007 found that 7% of food products bearing warning or advisory labels for peanuts are indeed contaminated with peanut protein. And 33% of food products listing peanut as a minor ingredient contain detectable levels of peanut in them. The level of contamination is in amounts that in some cases could elicit allergic reactions. These warning labels can appear in numerous formats although the three most common statements are: (1) "may contain peanut," (2) "manufactured on shared equipment with peanuts," and (3) manufactured in the same facility with peanuts."

Unfortunately, the same study showed that consumers with food allergies are increasingly ignoring allergy advisory labels and eating food products bearing such warnings. A risk exists to consumers who choose to eat such foods because food products with advisory labeling do contain detectable levels of peanuts. It's similar to playing Russian roulette. The same study showed that food products bearing "shared facility" warnings are just as likely if not more likely to be contaminated with peanut as food products marked with "may contain" warnings. The wording of the warning did not influence the likelihood of finding detectable peanut in a food product. All of the allergy warning statements, regardless of wording, should be taken to mean that some level of risk exists.

Individuals who are peanut allergic should avoid packaged food products with peanut listed as a minor ingredient or bearing an allergy warning statement for peanuts.

Which food allergies are most commonly outgrown?
The majority of children outgrow their food allergies, including those with a history of severe reactions. Some food allergies are more commonly outgrown than others. Most children allergic to cow's milk, egg, soy and wheat will outgrow their allergy between the ages of 3 and 18 years of age. Approximately 80% of children will eventually outgrow their milk allergy. Roughly 60-70% of children will outgrow their egg allergy and even more children will become less sensitive to eggs over time. And approximately 80-90% of children will outgrow their allergy to soy or wheat over time. Your allergist/immunologist can evaluate your child for the disappearance of a food allergy.

Which food allergies are not commonly outgrown?
Some food allergies are less commonly outgrown than others and these include peanut, tree nuts, fish, and shellfish. Clinicians used to believe that peanut allergy is life-long, but more recent studies show that approximately 20% of peanut-allergic children outgrow their allergy. Less than 10% of children outgrow their allergy to tree nuts (walnuts, cashews, almonds, pistachios, hazelnut, pecans, brazil nuts, etc). Food allergy to fish and shellfish commonly develops later in life and tends to be the most persistent of food allergies. Approximately 3-4% of individuals with a food allergy to fish or shellfish will outgrow their allergy.

Are airlines allowed to serve peanuts?
Yes, airlines are allowed to serve peanuts. Currently, Air Canada, Air Tran, American, Continental, Frontier, Jet Blue, Midwest, United and US Airways do not serve individual packages of peanuts in coach class. Southwest will not serve peanuts on a particular flight if alerted that a peanut allergic individual is on board. However, these airlines may serve food that contains peanuts or tree nuts or trace amounts of peanuts. Do not eat airline meals or snacks! Bring your own safe food with you to eat on board.

Airlines cannot prevent other passengers from bringing peanuts on board. No airline can guarantee a peanut-free flight or food offerings. Some airlines (e.g., Delta) will provide a "peanut-free buffer zone" around a peanut allergic passenger if alerted that such a passenger is on board. Other airlines (e.g., Jet Blue) will make an announcement asking passengers to voluntarily refrain from eating peanut products.

To help you stay safe on an airplane: Wipe down the tray table, arm rests and seat. Bring your own food. Always have your emergency medications handy. And choose flights in the morning whenever possible, as planes are cleanest at this time. It is important to remember that peanut allergic individuals fly safely every day without any reactions.

My daughter has a peanut allergy. Will my younger son develop one as well?
A study on the genetics of peanut allergy found that if a child has a peanut allergy, the chance that a sibling will also be allergic to peanuts is approximately 7%. This risk is compared with a 1-2% risk in a child from a family without a history of any allergies. Because of this increased risk, your allergist/immunologist may recommend testing younger siblings for a peanut allergy before they ingest peanut. You can discuss with your allergist/immunologist at what point to undertake such testing.

Why is my child's school nut-free? What food can she bring?
The basis for peanut- and tree nut-free schools has to do with the somewhat unique nature of these food allergies. Although uncommon, individuals with peanut and tree nut allergies can react to traces of nut dust in the air. Peanut and tree nuts also contain oils that leave residues behind on hands and surfaces. Hands and tables can be cleaned with soap and common household cleaners respectively, but it can be difficult to clean tables in the middle of lunch and contaminated doorknobs may be missed. Many schools have reacted by establishing peanut and tree nut-free lunch tables or entire schools. For parents who are new to packing lunches or snacks for a nut-free classroom, the learning curve can be steep and challenging.

Thanks to the Food Allergen Labeling and Consumer Protection Act (FALCPA) passed in 2004, peanuts and tree nuts must be clearly identified on an ingredient label if they are used in a food product. Foods that pose a risk of cross-contamination during manufacturing are not allowed in nut-free classrooms. Look for warning labels such as "may contain traces of peanuts," "manufactured on shared equipment with peanuts," or "manufactured at the same facility as peanuts." Manufacturing practices and ingredients can change and it is essential to read the label each time you buy a food product at the store. It is important to follow school directions provided on this topic. Some foods that are good to bring to a nut-free classroom include fresh fruit (bananas, apples, clementines, etc), raisins and other dried fruit, applesauce, vegetables, cheese (string cheese sticks), pudding cups, juice, or water.

Can food allergies trigger eczema?
Eczema can be triggered by allergic triggers such as food or environmental allergens or non-allergic triggers such as stress, dry weather, or infections. Food allergies can either cause or worsen eczema in those with allergic eczema. This is most likely in young children and infants. Foods that have been implicated include wheat, milk, soy, eggs, and peanuts. Skin testing conducted by an allergist can help clarify which foods may be triggering eczema. An allergist may recommend avoidance of specific foods and then reintroduction in the future to see if a specific food truly was responsible for the symptoms or if an individual has outgrown the food allergy.

My child has eczema which appears to be a skin disease. How could an allergist/immunologist help treat this?
Eczema or atopic dermatitis is often triggered by an allergy to an environmental allergen or food. It typically affects the face, neck, ears, elbows, hands, knees, and ankles. It is the most common chronic skin disease in young children but can affect a patient of any age. Because eczema can be made worse by an allergy, an allergist/immunologist is best trained to determine possible triggers, provide instructions in avoidance of allergens and other non-allergic triggers, patient education, treatment strategies, preventative measures, and management.

What types of soap are best for children with eczema or atopic dermatitis?
There is no one agreed upon best kind of soap or skin cleanser for eczema or atopic dermatitis sufferers. An individual with eczema should avoid harsh detergents or drying soaps. Our skin is actually not as alkaline as most soaps. Our skin's normal pH is about 4 to 5, whereas the average pH of soap is 9 to 10. Soap increases the pH of our skin to a non-physiologic pH that can worsen eczema or atopic dermatitis. Instead, a mild non-soap skin cleanser is generally best. Non-soap skin cleansers are free of sodium laurel sulfate which can aggravate eczema or atopic dermatitis. Examples of non-soap skin cleansers include Dove® Sensitive Skin Unscented Beauty Bar, Aquaphor® Gentle Wash, AVEENO® Advanced Care Wash, Basis® Sensitive Skin Bar, CeraVe™ Hydrating Cleanser, and Cetaphil® Gentle Cleansing Bar. When bathing, wash needed areas only. Avoid using anything in the shower or bath that will abrade the skin, such as a washcloth, sponge, or loofah. And after bathing, pat skin dry rather than rub dry. And remember to moisturize immediately after bathing (within 3 minutes) to seal in moisture.

What are bleach baths? How do they work?
Atopic dermatitis (eczema) is a chronic itchy skin condition that primarily affects children. It can be exacerbated or triggered by many factors including environmental allergies, irritants like harsh soaps, food allergies, dry weather conditions, and sweating. Another factor contributing to the flares of this condition is Staphylococcus aureus, a type of bacteria that frequently colonizes and infects the skin of individuals with atopic dermatitis.

Bleach baths are sometimes recommended as part of a treatment regimen for individuals with atopic dermatitis to decrease their bacterial skin colonization and infection. Bleach baths turn the bathtub at home into a swimming pool. A ¼ to ½ cup of common household bleach is added to a tub-full of water. Individuals with atopic dermatitis are instructed to soak 2-3 times per week for 5-10 minutes each time and then rinse off with fresh water. Researchers recently found that children treated with the diluted bleach baths had a reduction in eczema severity that was five times greater than those in the placebo group (plain water, no bleach). The dilute bleach baths were very well tolerated.

How do allergy shots work?
Sometimes people think allergies are the result of a weak immune system. To the contrary, allergies occur when the immune system overreacts to proteins called allergens. For instance, if someone is allergic to cats, their immune system goes into overdrive when they are exposed to cat allergen, releasing histamine and other chemicals. Symptoms then occur such as sneezing, runny nose, nasal congestion and itchy, watery eyes.

Allergy shots help to decrease this overreaction by giving small but increasing amounts of the allergen(s) to which someone is allergic. This works to calm down, or desensitize, the immune system to those allergens. When research has been done regarding these changes, allergy shots have been shown to decrease IgE, which is the allergic antibody, along with numerous other changes.

What really matters is that allergy shots help to control hay fever, asthma and sinus problems caused by allergies. Talk to your board-certified allergist about whether allergy shots can help you.

Are allergy shots safe?
Allergy shots are very safe. There are two types of reactions that can occur after allergy shots are administered. The first is known as a large local reaction. This is local swelling and redness at the site of the allergy shot and can occur right after an allergy shot or many hours later. These are relatively common and cause local discomfort only and are not associated with a severe reaction.

Systemic reactions are not as common and can be mild or serious. Severe systemic reactions are associated with trouble breathing, dizziness and/or a rash. These are rare and tend to occur in the first 30 minutes after a shot. That is why it is recommended that shots be given in a physician's office where the medical staff is capable of treating someone who is having an allergic reaction.

What benefits do allergy shots have over other treatment?
Allergy shots are given to individuals with environmental allergies or hay fever, some people with asthma, and for those with severe allergies to certain stinging insects such as bees or wasps.

Allergy shots are usually given weekly for about 6-7 months and then monthly for 3 to 5 years. This often leads to long-lasting improvement in symptoms, often without other medications. The benefits of allergy shots tend to last even after they are discontinued—this is one of the major differences between allergy shots and medications. Allergy shots may also prevent the development of new allergies and asthma in a child.

Can allergy shots help with my asthma?
It depends. If you have allergic asthma, asthma triggered by exposure to allergens such as pollens, molds, dust mites, or cat or dog dander, allergy shots may help improve your asthma. However, if your asthma is triggered by strenuous exercise, cigarette smoke, viral or bacterial infections, acid reflux, or anxiety, allergy shots are unlikely to help. Allergy shots (or immunotherapy) are aimed at increasing your tolerance to allergens that trigger your symptoms every time you are exposed to them. Allergy shots are recommended for patients with allergic asthma. Allergy shots can lead to decreased or no asthma or allergy symptoms when you are again exposed to the allergen(s) in the shot. Over time, this can lead to improved control of your asthma.

When are pollen levels typically the highest during the day?
Pollen counts are highest between 5 am and 10 am. They also tend to be highest on warm, dry, breezy days and lowest on wet, chilly days. The amount of pollen in the air determines whether allergic rhinitis or hay fever symptoms will develop. It can be hard to avoid pollen during spring through fall because it can be everywhere.

Some simple steps can help to reduce your exposure to pollen and thus reduce your symptoms: Limit outdoor activity when the pollen count is high. Plan outdoor activities later in the day when pollen counts are typically lower. This will decrease the amount of pollen you inhale. Pollen tends to stick to clothing, skin and hair. Shower and change your clothes immediately after spending time outdoors. And keep your windows closed and air conditioning on at home and in the car during pollen seasons to reduce your exposure to pollen.

When is it best to start medications for spring tree pollen allergy?
The majority of allergy medications work best if started before tree pollen is in the air each spring and allergy symptoms develop. When an allergic individual comes into contact with an allergen, such as tree, grass, or ragweed pollen, the cells in his or her nose and eyes release chemicals, including histamine and leukotrienes, and others. These chemicals cause sneezing, an itchy, runny nose, itchy, red eyes, as well as other symptoms. If you already have an allergy medication on board when you first come into contact with tree pollen in the spring, the medication will prevent the release of histamine and other chemicals. By preventing the release of these chemicals, allergy symptoms are prevented from developing or are much less severe. If you know that you are allergic to tree pollen in the spring or ragweed pollen in the fall, it is best to start your allergy medications two to three weeks before the pollen season starts.

My doctor told me to reduce my exposure to dust mites. Aren't they everywhere?
Dust mites are little insects that are not visible to naked eye because they are only 250 to 300 microns in length. They feed on human skin flakes and it is their fecal matter that causes allergies. Humidity and temperature increase dust mite levels. Although dust mites make a part of the dust found in homes, mattresses and pillows are the major source of dust mite allergen. Other sources of dust mites include carpets and upholstered furniture.

Plastic covers or dust mite impervious covers sold commercially are the best way to reduce dust mite exposure. Other measures to reduce dust mites include keeping humidity less than 50%, washing sheets and pillow covers weekly in hot water, freezing or washing stuffed animals and frequent vacuuming of carpets. Replacing carpets with hard wood or stone floor reduces dust mite exposure as well.