An estimated 4 to 6 percent of infants and 1 to 2 percent of children are diagnosed with true food allergies. The most common food allergies in children include milk, eggs, peanuts, soybeans, tree nuts, wheat, fish, and shellfish. Children are likely to grow out of allergies to milk and soy by the time they are about three years old. Food allergies to peanuts, fish, shellfish, wheat, and eggs are seldom outgrown. Anyone can develop food allergies, but those with a family history are at higher risk. A true food allergy sets off a chain of immune system reactions when the offending food is consumed. When a child eats a food she is allergic to, her body releases antibodies that cause reactions such as skin rashes, runny nose, watery eyes, nausea, wheezing, or diarrhea. In rare cases, food allergies can cause anaphylactic shock, a much more severe reaction. Some food allergies symptoms in children show up immediately, while others may take a few days.

Food allergies are different than food sensitivities. Food sensitivity refers to an oral sensitivity that a child may experience when eating a specific food. The food may cause tingling, burning, itching, or other discomfort in the mouth or on the lips. It can progress to swelling in the mouth or throat, much like other serious allergic reactions. If your child experiences these types of symptoms, avoid the food and speak to your doctor.

If your child is at a high risk of developing food allergies, you should not offer solid foods until he is at least six months old. Once your child begins solid foods, avoid egg whites, cow's milk, and wheat until your infant it at least one year old. To be on the safe side also avoid peanuts (including peanut butter) until your child is at least three, especially if either parent has a history of a peanut allergy. Be careful of feeding your child mixed-ingredient foods or mixed entrees, such as casseroles, unless you are sure that he is not allergic to any of the individual ingredients. These types of food also make it difficult to determine food allergies. You should avoid adding any seasonings to your child's food until he is a bit older. Introduce new foods every three to five days — if your child is going to have an allergic reaction to a food, symptoms will either show up immediately or within this time frame.

If you suspect an allergic reaction to a certain food, keep a food diary for a few weeks and record what foods your child has been eating, especially recently introduced foods, and when he developed symptoms. Speak to your pediatrician, who may refer you to an allergist to ensure it is a true food allergy. An allergist may do some testing to determine the exact allergy. Avoiding a particular food in your child's diet can sometimes be more difficult than it sounds. Foods can show up as ingredients in other foods, and depending on the severity of the allergy, a little bit may be enough to trigger a severe reaction.

It is essential to learn all you can about your child's specific food allergy. A registered dietitian can help. Your doctor should be the one to let you know when it might be safe to reintroduce the food. If your child experiences more severe symptoms, speak with your pediatrician immediately.