If you and your spouse both have allergies then, according to the American Academy of Pediatrics, your child has a 60 to 70 percent chance of also having them. This fact may lead you to advocate for having your child tested -- especially if you have a history of asthma or other severe allergies. However, many pediatricians resist testing infants younger than 6 months or 1 year. Although age is not strictly prohibitive for allergy testing, several factors must be considered in testing infants.
Avoidance Test Contraindications
Doctors who suspect your child has allergies typically begin by asking you to avoid highly suspect items, such as your family pet or high-risk foods. Although this seems simple, avoiding all contact with an allergen is often more difficult than it appears. For example, even if your child is not eating solid foods yet, allergens can be passed through your breast milk, and some children react to certain ingredients in baby foods or formulas. Avoidance tests often provide a good starting place, but they should not be relied on if severe allergies are suspected because they are so difficult to perform accurately.
Skin Test Contraindications
Skin prick tests are the most sensitive allergy tests available. However, your baby's immune system is still developing, and therefore definitive diagnosis of allergies is difficult to make. Tests administered to very young children several months apart often yield significantly different results. This is both because a baby must be exposed to something before she can develop an allergy to it and because many children outgrow early allergies. Skin tests also carry a slight risk of a severe reaction. As a result, many doctors avoid skin tests on children younger than age 2, most avoid them on infants younger than 6 months.
Blood Test Contraindications
In cases where severe allergies are suspected, a doctor may order a blood test instead of a skin test. Blood tests do not carry the risk of severe reaction that skin tests do, but they are more expensive and they do not catch as many allergies. According to BabyCenter, blood tests are even less sensitive in infants than they are in older children and adults; therefore, a negative result should be treated very cautiously. Despite this, they may be preferable to skin tests because they are faster than skin tests and cause less discomfort.
False Negatives
Many allergic reactions do not appear until a child has been exposed to the allergen several times. This means that your child may be able to tolerate your family pet for several months before suddenly becoming allergic. Thus, if you test your child too soon, his results may be negative when, in fact, he will develop allergies. The false negative might cause you to miss important signs as he gets older and may even result in your seeking treatment for chronic colds when your child needs allergy treatments. As a result, many doctors recommend waiting until a child is older to test.
