A food allergy is an abnormal response of the body to a certain food. It happens when the body's immune system, which normally fights infections, sees the food as an invader. This leads to an allergic reaction.

Food allergy causes an immune system response, causing symptoms in your child that range from uncomfortable to life-threatening. Food intolerance does not affect the immune system, although some symptoms may be the same as in food allergies.

Causes

Before having a food allergy reaction, a sensitive child must have been exposed to the food at least once before, or could also be sensitised through breast milk. It is the second time your child eats the food that the allergic symptoms happen. At that time, when IgE antibodies react with the food, histamines are released, which can cause your child to experience hives, asthma, itching in the mouth, trouble breathing, stomach pains, vomiting, and/or diarrhoea.

Common Food Allergies

• Milk
• Eggs
• Wheat
• Soy
• Sesame
• Peanuts
• Fish
• Shellfish

Symptoms

Allergic symptoms may begin within minutes to an hour after ingesting the food.

• Wheezing.
• Trouble breathing.
• Coughing.
• Hoarseness.
• Throat tightness.
• Belly pain.
• Vomiting.
• Diarrhoea.
• Itchy, watery, or swollen eyes.
• Hives.
• Red spots.
• Swelling.
• A drop in blood pressure, causing lightheadedness or loss of consciousness (passing out) sometimes, an allergy can cause a severe reaction called anaphylaxis. Anaphylaxis might start with some of the same symptoms as a less severe reaction, but can quickly get worse. The baby may have trouble breathing or pass out. More than one part of the body might be involved. If it isn't treated with injectable epinephrine, anaphylaxis can be life-threatening.

Milk and soy allergy

Allergies to milk and soy are usually seen in infants and young children. Often, these symptoms are unlike the symptoms of other allergies, but, rather, may include the following:

• Colic (fussy baby).
• Blood in your child's stool.
• Poor growth.
• Often, your child's doctor will change your baby's formula to a soy formula or breast milk if it is thought he or she is allergic to milk. If your child has problems with soy formula, your child's health care provider might change him or her to an easily digested hypoallergenic formula. The symptoms of a milk or soy allergy may resemble other problems or medical conditions. Always consult your child's doctor for a diagnosis.

Remedies

• If possible, breastfeed your infant for the first six months.
• Do not give solid foods until your child is 6 months of age or older.
• Avoid cow's milk, wheat, eggs, peanuts, and fish during your child's first year of life.

How is a food allergy diagnosed?

If your child might have a food allergy, the doctor will ask about:

• Your child's symptoms.
• The time it takes between eating a particular food and the start of symptoms.
• Whether any family members have allergies or conditions like eczema and asthma.

The doctor might refer you to an allergist (allergy specialist doctor), who will ask more questions and do a physical exam. The allergist probably will order tests to help make a diagnosis, such as:

• A skin test. This test involves placing liquid extracts of food allergens on your child's forearm or back, pricking the skin, and waiting to see if reddish raised spots (called wheals) form.
• A positive test on food shows that your child might be sensitive to that food.
• Blood tests to check the blood for IgE antibodies to specific foods.