Soy Allergy

What is a Soy Allergy?

Soy allergy is one of the most common food allergies in infants and children. This food allergy is often outgrown by the age of three. Symptoms of a soy allergy may be mild or more severe and can include:

  • Hives, itching, or eczema
  • Tingling sensation in the mouth
  • Swelling of lips, face, tongue, throat or other parts of the body
  • Wheezing, runny nose, or trouble breathing
  • Abdominal pain, diarrhea, nausea or vomiting
  • Dizziness, lightheadedness, or fainting

Some people may have a serious reaction to soy called anaphylaxis, which is potentially life-threatening if it is not treated. Discuss symptoms and treatment options with your doctor. Call 911 if breathing becomes difficult.


If you are allergic to soy, the only way to prevent an allergic reaction is to avoid soybeans and all soy products.

Label Reading

Soy is used in many processed foods. It is important to read labels carefully in order to avoid products that may contain soy. Some ingredient lists may not include the word "soy," but that doesn't mean that the product is soy-free.

General Guidelines to Help You Avoid Soy Products:

1. Check to see if soy is listed in the ingredients. Check the lists below for other names used for soy.

2. Look for the phrase "contains soy" somewhere on the package.

3. Call the manufacturer if you have any doubts. It's better to be safe than sorry when it comes to food allergies.

Common Sources of Soy

These items contain soy and should be avoided:

  • Bean curd
  • Edamame
  • Hydrolyzed soy protein
  • Lecithin
  • Miso soup
  • miso paste
  • Natto
  • Shoyu sauce
  • Soya
  • Soy albumin
  • Soybeans
  • Soy flour, soy grits, soy milk, soy nuts, soy oil, soy sauce, soy sprouts
  • Tamari
  • Tempeh
  • Textured soy protein (TSP)
  • Textured vegetable protein (TVP)
  • TofuVegetarian hot dogs, burgers, sausages

These label ingredients may or may not contain soy protein. Read labels carefully. If unsure, call the manufacturer:

  • Cereals
  • Formulas for infants and toddlers
  • Hydrolyzed plant protein
  • Hydrolyzed vegetable protein
  • Imitation bacon bits
  • Margarines made with soybean oil
  • Meal replacement shakes
  • Non-dairy frozen desserts
  • Natural flavoring
  • Processed meats
  • Protein powder
  • Surimi (imitation seafood)
  • Vegetable broth

Non-food items may contain soy

Allergen labeling does not apply to non-food items like soap, lotion, and medications. Some people will have reactions to these items as well. To be safe, check labels on these products to make sure they are soy-free.

Avoid Cross Contamination

Even though a product may be soy-free, it can become allergenic if it comes into contact with a soy product. It is important to take the following precautions:

1. Sanitize cutting boards, knives, forks, and anything that touches food.

2. Prepare soy-free items first before preparing soy-containing foods.

3. Do not re-use frying oil if a food containing soy was fried in that oil.

4. Cover and label foods that are soy free so that they are separated from foods that contain soy.

5. Store soy-free food on separate shelves in the refrigerator and pantry.

Soy Oil and Soy Lecithin

Soy oil and soy lecithin are highly processed forms of soy. They have less of the soy protein that causes the food allergy reaction. Some people tolerate soy oil and lecithin, while others do not. Ask your doctor if you should avoid these forms of soy.

Useful Resources

Food Allergy and Anaphylaxis Network


American Academy of Allergy, Asthma, and Immunology


Reviewed by health care specialists at UCSF Medical Center.

This information is for educational purposes only and is not intended to replace the advice of your doctor or health care provider. We encourage you to discuss with your doctor any questions or concerns you may have.

Related Information

UCSF Clinics & Centers

Allergy & Immunology
400 Parnassus Ave., Fifth Floor
San Francisco, CA 94143
Phone: (415) 353-2725
Fax: (415) 353-2568