There's no question that kids can be picky eaters, but for some kids,  staying away from certain foods is a necessity. About 3 to 8 percent of  kids have food allergies, some of them severe enough to be  life-threatening. That's why you need to know if your child is truly allergic to  foods.

  Why do food allergies occur? Food allergies occur after a child is first exposed to a food. The second time the child eats that food, the body's immune system may react as if it were a foreign invader. The body creates histamines. If you think your child is allergic to a particular food, look for these histamine-related symptoms:  
hives
itching in the mouth
wheezing
throat tightness
asthma
stomach pain
vomiting
diarrhea

 Severe allergic reactions to foods can be life-threatening. A severe reaction may include anaphylaxis, in which breathing passages swell up, breathing becomes difficult, blood pressure drops, and shock and even death may follow. If your child has difficulty breathing, call for emergency help right away.  

Here are some of the more common food allergy culprits: eggs
peanuts
wheat
shellfish (shrimp, lobster, etc)
citrus fruit
nuts
beef
veal
fish
chocolate, strawberries, corn or tomatoes (more rarely)

 On the other hand, some foods don't cause true allergies. Rather, they create "intolerance" to the food. Lactose intolerance, for example, causes some of the same symptoms of food allergy, such as vomiting or  diarrhea. These symptoms aren't the result of an allergic reaction, but are the result of deficiency of the enzyme lactase, which normally breaks  down the sugar in dairy products.

  What can you do?
If you suspect your child has a food allergy, don't guess. Talk to her doctor, who can help pinpoint the culprit through elimination and, if necessary, testing.  

Once your child is diagnosed with a food allergy, the only treatment is avoidance, which can be a challenge when the allergy is to a common food, such as wheat. You'll need to read labels carefully and become aware of what ingredients are normally found in restaurant foods and foods prepared for events such as birthday parties or picnics.