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Overview

A member of the legume family, soy is a common ingredient in infant formulas and many other processed foods. In young children, soy is one of the most common food allergens. Typically, allergic reactions first appear in infants and children under 3, and most of them outgrow the allergy by age 10.

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Soy Allergy Symptoms

  • Rash or hives (urticaria)
  • Itching in the mouth
  • Nausea, vomiting or diarrhea
  • Stuffy or runny nose
  • Wheezing or other asthma symptoms

For more information on soy allergy symptoms click here.

Rarely, a soy allergy will cause anaphylaxis, a potentially fatal reaction in which the throat swells up, blood pressure drops and breathing is impaired. Immediate treatment with epinephrine, using an auto-injector, can reverse these symptoms. Do you suspect your child has a soy allergy? The symptoms could indicate a serious issue. Don’t delay: Find an allergist today.

Common Triggers of a Soy Allergy

  • Soy and soy products (including some infant formulas), soy milk and soy sauce

Soy Allergy Management

  • Avoid products containing soy.
  • Read labels carefully.

For more information on egg allergy management click here.

Symptoms

Symptoms of a soy allergy include:

  • Rash or hives (urticaria)
  • Itching in the mouth
  • Nausea, vomiting or diarrhea
  • Stuffy or runny nose
  • Wheezing or other asthma symptoms

Rarely, a soy allergy will cause anaphylaxis, a potentially life-threatening reaction that impairs breathing, causes a sudden drop in blood pressure and can send the body into shock. The only medication that can treat anaphylaxis is epinephrine (adrenaline), administered through an auto-injector as soon as symptoms are apparent.

If you or your child experiences any of these symptoms after eating soybeans or a product containing soy, see an allergist.

Diagnosis

The allergist will take a history and conduct a physical examination. You may be asked to keep a food diary, noting not just what is eaten, but what symptoms occur after food is consumed.

In addition, the allergist may recommend a skin-prick test or a blood test, both of which check for the presence of immunoglobulin E (IgE) antibodies to soy protein.

In the skin-prick test, a small amount of a liquid containing soy protein is placed on the back or forearm, which is then pricked with a small, sterile probe to allow the liquid to seep into the skin. The presence within 15 to 20 minutes of a raised, reddish spot can indicate an allergy. In the blood test, a blood sample is sent to a laboratory to test for the presence of IgE antibodies; the result is reported as a numerical value.

If these tests aren’t definitive, the allergist may order an oral food challenge. Under medical supervision, the person being tested will eat small amounts of an item containing soy to see whether symptoms develop. Because of the possibility that a reaction could be severe, this test is conducted in your allergist’s office or at a food challenge center with emergency equipment and medication on hand.

Management and Treatment

As with other food allergies, the best way to manage a soy allergy is to avoid consuming products that contain soy.

Soy is one of the eight allergens that fall under the labeling requirements of the Food Allergen Labeling and Consumer Protection Act of 2004. This means that manufacturers of packaged food items sold in the United States and containing soy or a soy-based ingredient must state, in clear language, the presence of soy in the product.

Soy or derivatives of soy are found in some infant formulas, canned broths, soups, canned tuna, processed meats and hot dogs, energy bars, baked goods and many other processed foods. Soy also is a common ingredient in Asian cuisine and is sometimes contained in chicken nuggets, low-fat peanut butter, alternative nut butters and even vodka. People with a soy allergy should not consume soy milk, soy yogurt or ice cream, edamame, miso, tempeh and tofu.

Most individuals allergic to soy can safely consume highly refined soybean oil. Ask your allergist about avoiding this ingredient. Also, be cautious when eating foods that have been fried in any type of oil, due to the risk of cross-contact: If a soy-containing food is fried in oil, that oil will absorb certain soy proteins; if a different food that doesn’t contain soy is then fried in that same oil, consuming it could trigger an allergic reaction.

People with a soy allergy often can eat foods that contain soy lecithin — a mixture of fatty substances derived from soybean processing. If you have a soy allergy, ask your allergist if soy lecithin is safe for you.

People with a soy allergy sometimes wonder if they should also avoid peanuts — another legume that is a common allergy trigger. The answer is “not necessarily.” They are separate foods and their allergen triggers are unrelated. Soybeans also are unrelated to tree nuts such as almonds, walnuts and cashews. Those allergic to soy are no more likely to be allergic to tree nuts or peanuts than they would be to another food.

Talk to an allergist to take control of your soy allergy and live the life you want.