A:
Your question does not have an easy answer. It makes sense to test some children for allergies during infancy; for most others, testing is usually done when the children are older.
How young a child can be tested for allergies should be decided on a case-by-case basis. It depends on many things, such as what the child's symptoms are, what the doctor sees during the physical exam, whether something else besides allergies could explain the child's condition, and whether or not the child has a family history of asthma or allergies.
Infants rarely have "seasonal" allergies. These are allergy symptoms that happen at the same time every season. People generally need to be exposed to something more than once before allergies develop. Typically, you have to live through a few springs before pollen makes you sneeze.
Therefore, infants and young children are more likely to be allergic to things that they come in contact with many times, like dust mites, pet dander or food allergies. Fortunately, young children tend to grow out of some food allergies by age 5. Eggs, milk, wheat, and soy are good examples. On the other hand, some food allergies tend to stay throughout life, such as those for nuts and shellfish (lobster and shrimp).
If you have concerns, talk to your child's doctor. Decide together whether or not your child should be tested for allergies. Allergy tests can include:
- elimination
- challenge
- skin
- blood
The type of test will depend on which type of allergy the doctor suspects your child might have.
Henry H. Bernstein, D.O., is a senior lecturer in Pediatrics at Harvard Medical School. In addition, he is chief of General Academic Pediatrics at Children's Hospital at Dartmouth and professor of pediatrics at Dartmouth Medical School. He is the former associate chief of General Pediatrics and director of Primary Care at Children's Hospital Boston. 
