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Soy Allergy in Baby

Soybean allergy tends to be more common in babies and young children, with many outgrowing it as they age (1). Even though it is more common than others, it is estimated that only about 0.4% of infants in the US are allergic to soy.

Soybeans are legumes, just like beans, peas, lentils and peanuts. Up to 88% of people with soy allergies are also allergic or significantly sensitized to peanuts, although the reverse isn’t true (2). People with soy allergies are more likely to be allergic to major allergens like peanuts, tree nuts, egg, milk, and sesame, than to other legumes.

soy beans with a soybean plant with leaves in the middle

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How to Introduce Soy

While most of the research on allergen introduction has been done on peanuts, there is no research indicating harm in introducing other allergens using similar guidelines. For most children, we recommend to introduce food allergens “early and often.”

As with other allergens, introduce soy as the only new food that day. If you are looking for a more comprehensive guide to introducing allergens, then check out my Allergy Introduction Handbook.

  • Soy infant formula (not recommended for preterm infants)
  • Tofu
  • Smashed edamame
  • Soy yogurt
  • Tofu scramble
  • Silken tofu in a smoothie


The gold standard for the diagnosis of a food allergy is an oral challenge. While scary, it’s actually an easy test to perform: if the child eats the allergen, do they consistently produce a reaction? If so, they are allergic. Then, to confirm a diagnosis, a doctor may use a blood test or skin prick test. A medical professional should always make the diagnosis, because self-diagnosis can lead to unnecessary restriction.

How to Avoid Soy

Avoidance can be difficult, because soy is used in many processed foods. It’s very important to always check food labels. Companies must list soy clearly on the ingredients list in plain language or under the label in a statement that reads “Contains soy.” Most people will not react to soy lecithin, but speak with your allergist about your unique situation.

Some babies with soy allergies will have a cross-reaction to milk proteins in formulas as well. Because of this, they may benefit from a hypoallergenic formula. This is something that should be discussed with a physician or a pediatric dietitian familiar with your child.

Places to Check

Always ask about ingredients in foods that you did not make yourself. When eating at a restaurant, there is always a risk of cross-contact, so it is important to make it very clear that there is an allergy.

Soy is commonly used in Asian cuisine, such as Chinese, Indian, Indonesian, Thai and Vietnamese. There is always a risk of cross contact, even if you order a soy free item.

You can also sometimes find soy in vegetable gum, starch or broth, baked goods, canned soups, canned meats, cereals, cookies, crackers, snack bars, dairy products, infant formula, processed meats, sauces, sausages, and tempeh. It can also be in household products such as medication, lotions, soaps, moisturizers, and other personal care products.

Other Names for Soy

These terms mean that soy may be present:

  • Cold-pressed, expelled or extruded soy oil*
  • Edamame
  • Miso
  • Natto
  • Okara
  • Shoyu
  • Soy
  • Soya
  • Soybean
  • Soy protein
  • Soy sauce
  • Tamari
  • Tempeh
  • Textured vegetable protein (TVP)
  • Tofu

What about soybean oil?

Soybean oil does not typically cause a reaction in most people. Because of this, the FDA does not require that it is labeled on products. However, cold-pressed, expelled, or extruded soy oils should be avoided as they can contain small amounts of soy protein. You can speak with your allergist about your unique situation.

Reactions to Soy

Allergic reactions to soy are generally mild, but severe reactions have been reported. It is usually recommended for all kids with soy allergies to have an epi-pen with them at all times. Epinephrine is used to treat anaphylaxis, a severe reaction to allergies.

Skinmild rash, some hiveswidespread rash, hives all over the body
Faceitchy mouth, runny nose, sneezinglip swelling, tongue swelling
Gastrointestinalnauseavomiting, diarrhea
Airwaynonecoughing, wheezing, trouble breathing

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