Allergies tend to be hereditary. When one parent has an allergy to something, there's a 50 percent chance that his or her child will also have some type of allergy. If both parents are allergic, the chances go up to 75 or 80 percent. An allergy means that your body is overly sensitive to a certain harmless substance, and when it comes in contact with that substance, or allergen, it reacts to eradicate that invader. Allergic symptoms are the manifestation of the effort to get rid of the allergen that's bothering your immune system.
Most allergies show up by the time a child is 10 years old. You can perform an allergy skin test on infants as young as six months, but they're not considered totally reliable in kids younger than two years old. Before going ahead with any type of skin test, a doctor usually takes a few factors into account. First of all, he'll ask about your family history of allergies and asthma, as well as your child's history of allergic symptoms. Symptoms can include hives, a runny nose, wheezing, difficulty breathing, swelling, diarrhea and anaphylactic shock. The doctor will also probably examine your child to look for signs of allergies. Then he'll decide whether to do a skin test.
There are four types of allergy skin tests: scratch, puncture, prick and intradermal. The skin prick test is the most common. The idea behind these tests is to check your child's reaction to a variety of common allergens. Little drops of these allergens are poked into the skin, and then you wait about 15 minutes to see whether any red bumps appear on the site of the prick. The size of the red bumps indicates how sensitive your child is to a specific allergen. If someone is extremely sensitive, there's a chance that he'll go into anaphylactic shock and need immediate care. Sometimes, allergy skin tests are followed up or interchanged with the RAST blood test. Both are considered 90 percent accurate.