Recognizing Soy Allergy Symptoms

Soy allergy symptoms typically arise in children 3 and younger, and many outgrow the allergy. However, a soy allergy can develop at any age. A soy allergy may be to blame if you experience stomach problems, itching, a repetitive cough, or hives after eating soy-based foods. While soy is generally considered safe to consume, people with soy allergies should avoid it.

This article will help you identify products that contain soy, recognize soy allergy symptoms, and learn what to do if you or someone you care for has an allergic reaction to soy.

What Kinds of Products Cause Soy Allergy Symptoms?

If you have a soy allergy, any product containing soy or soy derivatives, which are ingredients obtained from processing soybeans, can cause symptoms. Soy and soy derivatives can be found in the following:

• Soy-based infant formulas
• Canned broths, soups, and tuna
• Processed meats, hot dogs, and chicken nuggets
• Energy bars and other baked goods
• Low-fat peanut butter and alternative butter
• Soy milk, yogurt, or ice cream
• Miso
• Tempeh
• Tofu
• Soy-based meat substitutes
• Soy sauce, tamari sauce, or teriyaki sauce
• Fried foods that have been fried in oil that is used to fry soy-containing foods

Soy Allergy Symptoms to Recognize

Soy allergy reactions can affect various organs and body systems, including your digestive and respiratory systems and your skin. In rare cases, people with severe soy allergies experience anaphylaxis.

Anaphylaxis

Rarely a soy allergy will cause anaphylaxis. This dangerous, potentially life-threatening reaction causes impaired breathing and a sudden drop in blood pressure which can send the body into shock. Symptoms may begin similarly to milder reactions but worsen within seconds or minutes of ingesting an allergen.

Additional symptoms of anaphylaxis include:

• Weak pulse
• Dizziness or fainting
• Confusion
• Skin rashes, itching, or hives
• Wheezing, shortness of breath, or difficulty breathing
• Swelling of the lips, tongue, or throat
• Gastrointestinal (GI) symptoms, such as stomach pain, diarrhea, or vomiting
• A sense of impending doom

If you or someone you care for is experiencing an anaphylactic reaction, administer epinephrine using an auto-injector (EpiPen) and call 911 immediately. Inform the dispatcher that epinephrine was given and more may be needed.

Gastrointestinal Symptoms

Some people with a soy allergy experience symptoms affecting their digestive system, specifically their GI tract. While most GI symptoms are uncomfortable, some may indicate a severe allergic reaction. Examples of GI symptoms include the following:

• Indigestion
• Stomach cramps
• Diarrhea
• Vomiting
• Swelling of the tongue or lips
  

Respiratory Symptoms

Similar to GI symptoms, respiratory symptoms can range from mild to severe. Respiratory symptoms of a soy allergy can include:

• Repetitive cough
• Wheezing
• Shortness of breath, difficulty breathing
  
• Tightness in throat
  

Skin Symptoms

Soy allergies may also produce skin-related symptoms, including the following:

• Itchiness
• Eczema
• Hives
• Pale or blue coloring

Treatment for Soy Allergy Symptoms and Reactions

Treatment for soy allergy symptoms and reactions varies depending on the body system affected and symptom severity.

Some of the treatments used for less severe but uncomfortable allergic reactions are:

• Nasal corticosteroids: Nose sprays that reduce swelling and relieve stuffy, runny, and itchy nose
• Antihistamines: Medications available in various forms (i.e., pill, liquid, etc.) that block the body's response to allergens, thus minimizing symptoms
• Decongestants: Medications that reduce nasal congestion
• Topical corticosteroids: Medications in the form of ointment or cream are applied directly to the skin to treat itchy skin reactions
• Oral corticosteroids: A healthcare provider may prescribe this type of oral medication to treat severe swelling and reduce the systemic effects of allergic reactions
• Epinephrine: This medication, such as the brand-named EpiPen, is the only medication used to reverse potentially life-threatening anaphylaxis

Testing to Confirm a Soy Allergy

If you suspect you or someone you care for has a soy allergy, consult an allergist (doctor specializing in allergies) for testing and diagnosis. There are several types of allergy tests to determine a soy allergy. A healthcare provider may do one or more of the following:

• Detailed questionnaire: A provider may ask questions about what you ate, how much, the length of time for symptoms to develop, types of symptoms, and how long they lasted. 
• Skin-prick test: This is an in-office test used to determine a soy allergy. In a skin-prick test, a drop of liquid containing the suspected allergen is placed on the skin, and the skin is punctured with a small probe to allow the liquid to seep into the skin. The test is considered positive if a small bump forms at the site.
• Blood tests: These are done by taking a small blood sample and measuring the amount of immunoglobulin E (IgE), an antibody that responds to soy, creating an allergic reaction.
• Oral food challenge: An oral food challenge must be performed in a clinic under strict supervision with an allergist, emergency medication, and equipment during the test. It is done by administering increasing amounts of the allergen (food) to see if there is an allergic reaction.
  

Soy-Free Foods and Ingredients

The best way to manage a soy allergy is to avoid eating soy and soy products. Under the labeling requirements of the Food Allergen Labeling and Consumer Protection Act of 2004, manufacturers of packaged food items sold in the United States must state if there are soy or soy derivatives in the product. Carefully read food labels and avoid products with any of the following ingredients:

• Hydrolyzed soy protein, soy protein concentrate, soy protein isolate, soy protein hydrolyzed
• Miso
• Edamame
• Natto
• Soy albumin
• Soy cheese, yogurt, ice cream, milk
• Soy fiber
• Soybean (curd or granules) or tofu
• Shoyu sauce, soy sauce, tamari
• Soy flour, grits, nuts
• Soy sprouts
• Tempeh
• Textured vegetable protein

Other possible sources:

• Hydrolyzed plant protein, hydrolyzed vegetable protein
• Natural flavorings
• Vegetable broth, gum, starch
• Soy based-flavorings
• Vitamin E

Summary

A soy allergy typically appears in infants and young children but can develop at any age. Soy allergy symptoms include rash, stomachache, itchy throat, cough, or stuffy nose after eating soy-based or soy-containing foods. Soy and its derivatives are found in many processed foods, sauces, and vegetarian protein products.

Always check food labels, as the Food and Drug Administration (FDA) requires manufacturers to state if soy is present. If you suspect you or someone you care for has a soy allergy, an allergist can confirm the diagnosis and guide treatment and management.