Q: Why do so many more kids have allergies these days, and why does my doctor recommend waiting until my kids are five to test them?
A: There are a number of theories as to why the rate of allergies and allergy-related problems (e.g., asthma) seem to be increasing in prevalence. My favourite theory is the hygiene hypothesis. If you grew up on a farm as one of 10 snotty-nosed children, and not too much attention was paid to keeping things scrupulously clean, versus your friend who was an only child living in a spotless condo, who do you think would land up with more allergies? Well, it’s not the farm kid. In fact, your exposure to germs and irritants from early on is thought to be protective in terms of developing allergies; so the very clean, sterile environment found in much of the developed world may be responsible for this phenomenon. Perhaps extending the five-second rule on food dropped on the floor to the 15-second rule may be worth considering?
Timing of testing depends on what you are testing for and how you are testing. There are different types of allergy tests, but perhaps the most popular is the skin “scratch” test. Testing for food allergies can be done at any age, but most docs would agree that testing for environmental allergies such as pollens and grasses should be delayed until later. This is because it may take years to become sensitized to allergens in the air and you may get a negative test even if allergic in the early years. A word of caution: just because you test positive for something does not necessarily mean you will have symptoms when exposed. So the tests have to be interpreted very carefully.
Looking for more? Be sure to read Dr. Friedman’s response to “Does my child need more sleep?”