Food Allergies: What You Need to Know

They can show up at any age. You might spend years allergy-free and then, seemingly out of the blue, you may break out in hives after eating a peanut butter and jelly sandwich. That’s a fairly common scenario, says Dr. William Reisacher, Professor of Otolaryngology and Director of Allergy Services at Weill Cornell Medicine. However, food allergies are especially common among babies and children.

The foods most often associated with allergy in children are milk, eggs and peanuts. Many kids outgrow their allergic reactions to milk and eggs, but peanut allergies tend to persist throughout a person’s life span. Allergies to tree nuts—mainly almonds, walnuts, hazelnuts, pecans, cashews and pistachios—as well as to fish and shellfish also tend to be lifelong.

The nine most common food allergens are:

  • Eggs
  • Milk and Dairy
  • Peanuts
  • Tree nuts
  • Fish
  • Shellfish
  • Wheat
  • Soy
  • Sesame (often in the form of humus, which contains tahini)

These foods account for about 90 percent of all food allergies.

What, exactly, is a food allergy?

According to the American College of Allergy, Asthma and Immunology (ACAAI), a food allergy occurs when your immune system overreacts to a food or a substance in a food. The immune system can mistakenly identify that food as a danger and trigger a protective response that proves to be anything but protective.

That definition may seem simple, but some of the terminology associated with food allergies can be confusing.

For example, says Dr. Reisacher, intolerance is a broad term that means a person’s body can’t tolerate a particular food. And sensitivity is what an allergist looks for via an allergy test. Technically, allergy specialists don’t test for allergies but for levels of sensitization to particular allergens.

A food allergy test measures the presence and levels of immunoglobulin E (IgE) antibodies against a variety of possible food allergens. People may have low levels of IgE antibodies to a particular food such that they never experience allergy symptoms. “But if you eat a large amount of the food to which you show sensitivity, an allergy could come to light,” he says.

A spectrum of symptoms

Symptoms of a food allergy can range from mild to severe. Per the ACAAI’s description, just because an initial reaction is mild doesn’t mean that all reactions will be similar. A food that triggered a mild stomach ache on one occasion might cause more severe symptoms the next time around.

The symptoms of a food allergy include the following:

  • Stomach cramps
  • Vomiting
  • Itching
  • Swelling
  • Hives
  • Shortness of breath
  • Wheezing
  • Tight, hoarse throat
  • Trouble swallowing
  • Weak pulse
  • Pale or blue skin color
  • Dizziness
  • Anaphylaxis

This last symptom—anaphylaxis—is the most severe of all. It’s a life-threatening, whole-body reaction that can interfere with your breathing, cause a dramatic drop in your blood pressure and send your body into shock. You may also experience a “feeling of doom,” Dr. Reisacher says. “Anaphylaxis must be treated as soon as possible with an injection of epinephrine. I urge everyone with a food allergy to carry an auto-injector, such as an EpiPen, at all times.”

Genetic issues

Food allergies tend to run in families. So do asthma and eczema, conditions that share allergy-like characteristics. Says Dr. Reisacher, “With eczema, the skin barrier is compromised, allowing substances to gain access to the body. And with food allergies, the gut barrier is compromised, meaning that food is not being processed properly.”

Children may experience two or even all three of these conditions—eczema, asthma and food allergies. The interrelationships between them are not well understood, at least not yet. However, “recent strides in genetics have ushered in new technologies and lines of research,” he says. And these all add up to hope for patients at any age who suffer from the signs and symptoms of these conditions.

Advice for parents

If you have a child with a food allergy, you know that avoiding the allergen is easier said than done. Labeling has made things easier, but some foods are so common that avoiding them completely can be difficult indeed. If you haven’t mastered the art of reading labels, now is the time to do so.

When it comes to keeping your child safe, eating out poses perhaps the biggest challenge of all. The waitstaff and even the kitchen staff may not always know “what’s in there” for every dish on the menu.

The ACAAI recommends using a “chef card,” available through many websites, that identifies your child’s allergy. Always tell your servers about it too, and ask to speak with the chef, if possible, to clarify which dishes on the menu are safe for your child.

But even in the safety of your home, children can have a lot of anxiety about food—understandably, says Dr. Reisacher. Food anxiety can affect every aspect of their lives, including their socialization. That’s why he collaborates with mental health professionals, who can help your entire family develop strategies for calming the outsize emotions that often go hand in hand with food allergies.

Safety first

Food allergies are serious business. In the United States, food allergy is the leading cause of anaphylaxis outside the hospital setting.

Once you or your child has been diagnosed with a food allergy, your allergist should prescribe an EpiPen and teach you how to use it. Keep it with you, and have two doses available.

And if you’re unsure whether a reaction is serious enough to warrant its use, use it anyway. It’s the only medication that can reverse the life-threatening symptoms of anaphylaxis, so be as quick and decisive as possible.

To make an appointment with an allergist at Weill Cornell Medicine, please visit here.