Dr. Rita Kachru
Pediatric allergist and immunologist
An allergy is basically an overreaction of the immune system to a substance thatís otherwise harmless to most people. So for instance, letís say itís milk that she eats. Either you like milk or you donít like milk, but itís not going to hurt you. But if youíre allergic to milk, your bodyís going to look at milk as if itís an invader, like a virus or a bacteria, and itís going to react against it. Usually when you drink milk, youíre not going to develop a rash, but if your body thinks itís a bacteria or a virus thatís coming into contact, it will respond with an immune response.
The way our body tries to get rid of viruses, bacteria, or in this case milk, an allergen, is inflammation. So in the skin, you could see hives, which are large, red blotches of skin. You could see eczema, which is dry patches of skin, usually in the elbows or behind the knees or on the torso or the cheeks. You could see difficulty breathing, wheezing, even voice changes, sometimes belly aches, diarrhea, and occasionally, if itís a severe inflammation thatís affecting the whole body, you can actually go into shock and it can be life-threatening.
Most Common Allergies Among Children
90% of food allergies are caused by milk, soy, wheat, egg, and peanut. The good news is that about 80 to 85% of milk, soy, wheat, and egg allergens will be outgrown in most children. About 20% of children allergic to peanuts will outgrow it. But having said that, even though the majority do get outgrown, the chances of having a severe reaction are there for these foods.
We donít know the exact science for why it happens, but we know that it has to do with gut maturity. You might completely avoid the food, which you might want to do for two reasons. One, you donít want them to have a severe reaction, so you avoid it. But two, you avoid it to give the gut time to mature. Then, when you reintroduce the food in one or two years, they seem to respond appropriately. The body seems to realize, ďWow, this isnít going to hurt me. I shouldnít really react against it.Ē Theyíre able to digest it.
The most common airborne allergies are, thereís indoors and outdoors. So indoor, you know, your favorite pets, so cats, dogs, rabbits. Mold. Thereís indoor mold. Dust mites are a very big allergen source. Cockroaches, which are a distant relative of the dust mite. The outdoors allergens are weeds, trees, grasses, the different pollens.
Other Common Allergies
Other common ones include medications, allergies to medications, which the most common type of medication that you would have an allergic reaction to are actually antibiotics, which are used to treat bacterial infections. And that can happen anytime during the treatment. So it can happen after the first dose, or it can happen after the tenth dose or eleventh dose. The reactions can vary from rashes, like what we talked about, hives, or it can be more severe, difficulty breathing and wheezing. If thereís any reaction that youíre concerned about, seek medical attention as soon as possible.
Symptoms to Look For
Look for an inappropriate inflammatory reaction where the body is looking at certain things as foreign. Letís take airborne reactions. Grass isnít going to hurt you, but if youíre allergic to grass, youíre going to mount a reaction to grass. If that reaction is just in the nose, you may have some sneezing, itching, congestion Ė those kind of irritable symptoms, but nothing that would harm you. But if that reaction goes further to the lungs, you can develop coughing, shortness of breath, wheezing. If it affects the skin, you can get hives. If itís a severe reaction, you can actually have anaphylaxis, which usually is more related to foods, but where you have a severe inflammatory reaction to the food.
Why Children Develop Allergies
The tendency to develop allergies is hereditary. So you usually get a history of either Mom or Dad having some sort of allergy. It doesnít have to be the same kind. But theyíll have hay fever or asthma. Having said that, there is a group of children that donít have a family history of allergy or no known family history of allergy, which may be, you know, an aunt or a distant uncle who had an allergic disease. So we know there is a genetic predisposition.
Testing for Allergies
Thereís two ways to allergy test. First of all, you take a good history to determine whether itís suspicious for this child to have allergies. And if it is determined, you know, that this child may have allergies, thereís 2 ways to test. You can either test by skin testing, where we take a device that looks like the tip of a pen and we put the different allergens on it and then we poke the skin. Takes about 20 minutes, and you look for an area of swelling or what we call induration.
The second way of doing it is by blood test, where we draw the patientís blood and we send it to a lab, and then we do the same thing in a lab. We add the different things that we want to test. Both are good tests. The skin test is, in my view, a little bit more sensitive because itís actually going on the skin. And you get a quick reaction. You know right away what theyíre allergic to. The blood test is useful if you came to me and said, my child had milk and had such a severe reaction and had difficulty breathing and wheezing. Well, Iím not going to come near your child with a milk. And in that case, I would definitely do a blood test first. But theyíre both reliable tests.
The older a child is, the better their immune system is and the better response youíll get. So up to age 6 months, the child basically has their momís immune system. Sometimes youíll get false test results because youíre actually picking up the momís immune system. Having said that, Iíve skin tested down to 3 or 4 months in kids who have severe eczema or who have severe diarrhea and weíre concerned about a food allergy vs. intolerance, and weíll test those patients to make sure theyíre not allergic vs. intolerant.
Food Intolerance Versus Food Allergy
Food intolerance is more of an inability to digest the food properly. The reason we donít give babies pure cow milk is because they wouldnít be able to digest it. They are deficient in an enzyme to digest the milk. So theyíd have symptoms of colic, gassiness, diarrhea, vomiting, and the baby wouldnít grow well. An allergy is different. An allergy is an immune response. Itís as if the body is looking at the milk like itís a virus or bacteria and responding with a strong inflammatory reaction which could be fatal.
Lactose intolerance is a type of food intolerance. People also have gluten intolerance or wheat intolerance. Youíre more likely to outgrow an allergy to a food than an intolerance to a type of food. For babies itís different. Your baby probably will outgrow it because itís during their first year of life and her digestive system is still maturing. But if you have a 10-year-old or an 11-year-old whoís intolerant, theyíre probably going to remain intolerant to that food.