Kids’ allergies: Triggers and testing

That constant congestion and sneezing probably has you wondering if your child has an allergy. And, that tummy ache after eating certain foods may very well mean a food allergy. Here, a paediatrician shares the top food and environmental triggers for kids, and why it’s worth getting your child tested for allergies – even if the symptoms seem mild.

Common childhood allergies

Allergies in children are very common – and on the rise, explains paediatrician Dr Leo Hamilton. “Overall, they appear to be increasing throughout the world,” he says. “While the exact increase is uncertain, with different countries reporting different increases, the cause is also uncertain; possible causes can include anything from changes in diet and increasing obesity to antibiotic overuse.”

But, whatever the reason, the fact is that kids have allergies all over the world, with environmental allergies being much more frequent than food allergies. While food allergies can appear in the first year of life, environmental allergies in kids usually don’t cause problems until after the age of two.

Environmental allergies

Here in Singapore, the most common environmental triggers are dust mites and tobacco smoke. In other countries, pollens and grasses are the most common triggers.

Unlike food allergies, environmental allergies typically do not cause life-threatening reactions. They typically show up as congestion, cough and a runny nose. They also often cause children who suffer from such allergies to experience symptoms including poor sleep, fatigue or snoring more than other kids. In some children, however, environmental allergies may trigger asthma attacks or cause a child’s asthma to worsen.

Ironically, Dr Leo says many doctors believe that too clean of an environment may lead to more allergies; it may actually be good for babies and older children to be exposed to animals, dirt and germs. However, this is being investigated, and no clear answers have been found quite yet.

Food allergies

While the exact reason for an increase of allergies is uncertain, Dr Leo says there is one change that does appear to be clear: “Restricting foods that tend to cause allergies does not lower the risk of developing an allergy.”

The most common food allergies include:

• cow’s milk
• eggs
• peanuts
• tree nuts
• fish
• shellfish
• wheat
• soy

Sesame has also become more common in the last few years, says Dr Leo.

Interestingly, studies over the last few decades have shown changes in the rates of reactions to specific foods. A recent study of Singaporean children noted that peanut is now the most common food allergy, whereas 15 years ago, bird’s nest was most common and peanut allergies were not noted at all. Rates also differ throughout the world – five percent of older Singaporean children and adults may have shellfish allergies, but less than one percent do in the US.

It’s important to note, however, that a food allergy is different than a food intolerance. Many children have food intolerances such as abdominal pain or bloating with dairy or gluten, or eczema flares, but this is not an allergy that requires complete avoidance like a peanut allergy does.

What parents should know about allergy testing

Because allergies – especially food allergies – can become more severe over time, Dr Leo says it’s a good idea to test for allergies if suspected, even if the initial symptoms are mild.

However, he says allergy testing can be confusing to interpret.

“First, testing may be positive even if no symptoms appear when eating that specific food. This is why most doctors recommend testing only for food that results in symptoms when consumed. For instance, it used to be that an allergy to any nut meant you were tested for all nuts. Many children tested positive for multiple nuts even though they could eat a particular nut without a reaction. As a result, children were put on restricted diets to avoid foods that did not cause problems.”

Adding to the confusion, he says, is the fact that allergy tests can be negative but a child can still have a serious allergy. Therefore, the “gold standard” of not having an allergy is when your child can eat a food item without having a reaction. And, if you react to a food, it is an allergy, no matter what a blood or skin test shows.

Dr Leo says there are two main allergy test options. One is a skin test to see if there is a visible reaction and the other involves blood testing for the level of antibodies in blood.

“The choice of which test is better is complex, so it’s something to talk to your doctor about,” he says.

At the end of the day, diagnosing a specific allergy can be difficult. If you suspect your child has an allergy, Dr Leo suggests talking to your doctor as the first step.

Find out more:

Dr Leo Hamilton is the resident paediatrician at Kids Clinic @ Novena. Since relocating here in 2011, he’s been caring for expat and Singaporean children from newborns at delivery to teenagers, with special interests including asthma, behavioural issues (primarily ADHD), teen health, and modern management of routine childhood illnesses such as ear infections, bronchiolitis and pneumonia.