Solutions for Soy Allergies in St. Louis

Soy Allergy

Struggling with soy allergies? Dr. Sonia Cajigal is a board-certified food allergist in St. Louis, Missouri that can help you navigate your soy allergy. Contact us at St. Louis Family Allergy to learn more about soy allergy symptoms, testing, and treatment options for you and your children.

“Dr. Cajigal was friendly, professional, and informative. She took the time to explain the tests and what was going on with my allergies. She is so knowledgeable and really cared about how I was feeling. I would highly recommend this practice if you suffer from allergies and asthma.”

– Sue D, July 2020

Soy Allergy Doctor Sonia Cajigal of St. Louis Family Allergy in St. Louis, Missouri
Soy allergy doctor Dr. Sonia Cajigal of St. Louis Family Allergy review badges and affiliations

About Soy Allergy

Soy Allergy Symptoms
Soy Allergy Testing
Soy Allergy Foods to Avoid
Soy Allergy Treatment
As a common ingredient in infant formulas, processed foods, and alternatives to dairy products, soy is one of the most common food allergens in young children. Soy allergy affects roughly 1 in every 250 infants (0.4%). However, it is possible to develop a soy allergy at any age, even if you’ve previously consumed soy without any issues. It is also common for infants to outgrow their soy allergy.

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in St. Louis, Missouri

Soy allergy foods

Soy Allergy Symptoms

A soy allergy can be either IgE-mediated, where symptoms develop immediately, or non-IgE-mediated, where symptoms develop over hours or days.

Soy allergy symptoms include:

  • Hives
  • Stomach cramps
  • Indigestion
  • Nausea
  • Vomiting
  • Diarrhea
  • Cough
  • Itching
  • Eczema
  • Tightness in your throat, hoarse voice
  • Shortness of breath, difficulty breathing
  • Swelling, can affect the tongue and/or lips
  • Anaphylaxis (difficulty breathing, increased heart rate, drop in blood pressure, dizziness and confusion)

Though rare, an IgE-mediated soy allergy can be deadly in the case of anaphylaxis. If you have severe allergic reaction symptoms, such as trouble breathing or swelling in your throat, call 911 or go to your nearest emergency room (ER) immediately.

Most non-IgE food allergies, including soy, aren’t life-threatening. However, soy is one of the most common triggers for non-IgE reactions in infants.

Soy Allergy Testing

Testing for soy allergy is similar to other food allergens, often involving a mix of medical history and allergy tests.

Medical History

Diagnosis begins with a thorough medical history where your allergist will ask you questions about your exposure to soy and your symptoms.

Typical questions include:

  • Do you have a family history of food allergies?
  • Have you ever been diagnosed with other food allergies?
  • What are your symptoms?
  • Do you take any over-the-counter (OTC) medications to treat your symptoms?
  • When do you notice your symptoms start to appear?
  • Do you keep a food journal?

At this stage, your allergist is evaluating soy and other potential allergens that may be the cause of your allergic reactions. If your medical history is consistent with a food allergy, your allergist will order tests to confirm or rule out soy.

Skin Test

The skin prick test is a common firstline allergy test where the skin is exposed to a small amount of soy to see if a reaction occurs.

Blood Test

Another method of allergy testing is the blood test, where a sample of your blood is withdrawn and sent to a lab. In the lab, your blood is exposed to soy to see if an immune response occurs.

Food Challenges

To definitively diagnose a soy allergy, your allergist may recommend a food challenge. This may be necessary if your medical history and soy allergy testing are inconsistent.

During an oral challenge, you’ll eat a small amount of soy under the supervision of your allergist. Your allergist will then observe you to see if a reaction develops. If you are able to tolerate a small amount of soy, your allergist will then increase the ‘dose’ until a reaction occurs or until it is determined that you can safely ingest soy.

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in St. Louis, Missouri

Woman reacting to soy allergy symptoms scratching rash on her neck

Soy Allergy Foods To Avoid

Check your food labels! Soy avoidance is the best way to manage a soy allergy.

In the United States, soy is one of the eight allergens that fall under the labeling requirements of the Food Allergen Labeling and Consumer Protection Act of 2004. Manufacturers of packaged food items that contain soy or a soy-based ingredient must state that the product contains soy.

While it is not possible for us to list every food product that contains soy, the following list covers most of the common foods, drinks, and ingredients that you should avoid if you have a soy allergy:

  • Soy in all forms, including soy flour, soy fiber, soy albumin and soy grits
  • Soy non-dairy alternatives, including soy milk, soy ice cream, soy cheese and soy yogurt
  • Soybean (curd and granules)
  • Soy protein (concentrate, isolate and hydrolyzed)
  • Soy nuts and soy sprouts
  • Soy sauce
  • Tofu and textured vegetable protein (TVP)
  • Edamame
  • Miso
  • Natto
  • Tempeh
  • Tamari
  • Hoisin

In addition to the above, the following ingredients may contain soy protein:

  • Natural and artificial flavoring
  • Vegetable broth
  • Vegetable gum and vegetable starch
  • Hydrolyzed plant protein
  • Hydrolyzed vegetable protein
  • Protein extender and protein filler

There are also several nonfood items that may contain soy, including:

  • Crayons
  • Cleaning products
  • Pet foods
  • Synthetic fabrics
  • Certain makeup and toiletry items

However, readers should be aware that U.S. food labeling laws don’t apply to nonfood items.

Food Challenges

A food challenge involves consuming a small amount of the suspected food allergen in a supervised, medical setting. This can help confirm an allergy or verify if you have outgrown one.

Skin Testing for Food Allergies

Dr. Cajigal may suggest a skin-prick test, where small volumes of food allergens (and controls) are placed on your skin and pricked with a sterile needle. After 20 minutes, the skin is re-examined for any bumps indicating an allergic reaction.

Blood Testing for Food Allergies

A blood test can measure the amount of antibody circulating in the blood in reaction to the specific food allergen of interest. This confirmatory test is often used to rule out a suspected allergen if skin testing shows no response.

Elimination Diet

You may be asked to temporarily eliminate specific foods from your diet for 2 to 4 weeks. If your allergic symptoms disappear during this time, it is likely that one or more of the eliminated foods was the allergen.

See a Food Allergy Doctor

in St. Louis, Missouri

Girl using EpiPen to treat severe soy allergy reaction

Soy Allergy Treatment

An epinephrine auto-injector (EpiPen) is typically prescribed to patients with soy allergy in the event that a serious, life-threatening reaction occurs. Epinephrine quickly reverses the symptoms of anaphylaxis. Individuals with soy allergy or parents of children with soy allergies should always have an EpiPen available.

For more information and resources on how to manage soy allergy and other food allergies, please see our food allergies page.


[1] American College of Allergy, Asthma & Immunology:
[2] Asthma and Allergy Foundation of America:
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St. Louis Family Allergy Google review score badge
"Dr. Cajigal was friendly, professional, and informative. She took the time to explain the tests and what was going on with my allergies. She is so knowledgeable and really cared about how I was feeling. I would highly recommend this practice if you suffer from allergies and asthma."

- Sue D, July 2020

“Dr Cajigal is a great listener. She trusts her patients instead of treating them as if they are not the experts of their own bodies. I really appreciate that (many doctors do not have that quality). She also immediately treats the symptoms instead of waiting to see if things clear. I use her for my children and myself. We have never left her office feeling as if it was a waste of time.”

– Stephanie, August 2020

"Great Allergist!"

- Ann H, December 2018

"She is the best."

- Stephen W, June 2020

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