Food Allergies
According to Mary Susan Spears, clinical dietitian at Children's Medical Center Dallas, an estimated 6 to 8 percent of young children and 4 percent of adults have a food allergy.

With an allergy, the immune system mistakenly identifies a food as harmful, triggering antibodies to fight the substance. Allergic symptoms usually develop within minutes and may include:

• Tingling in the mouth.
• Hives.
• Swelling of the lips, face, and tongue.
• Cramping or abdominal pain, diarrhea, nausea or vomiting.

More dangerous symptoms may include: 

• Breathing difficulties.
• Throat swelling.
• Chest wheezing.
• Dizziness.
• Low blood pressure.
• Shock and loss of consciousness.

"If your child has a food allergy, eating even the smallest amount of that food may trigger a serious reaction and the only treatment is the strict avoidance of the offending food," said Spears. "With food intolerance, you may be able to eat small amounts of problem foods without triggering a severe reaction."

Food intolerance
Childhood food intolerance is much more common than an actual food allergy response and doesn't involve the immune system. But it can cause some of the same gastrointestinal symptoms as a food allergy and certain foods will trigger symptoms for a number of medical conditions, such as irritable bowel syndrome, acid reflux and migraine headaches.

Diagnosing food intolerance is a bigger challenge. An example of common food sensitivity is when a child is lactose intolerant — the child doesn't have the stomach enzymes to fully digest sugar in milk products. The reaction to ingested milk can cause bloating, cramping or diarrhea.

When suspicious, test
 "It's wise to consult a physician if you have concerns or questions about your child's reaction to certain foods." said Spears. "The good news is that food allergies can be diagnosed through blood and skin testing."

Resources
Children's Medical Center