Soy allergy symptoms explained

Medically reviewed on June 16, 2022 by Jordan Stachel, M.S., RDN, CPT. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

Table of contents

• 4 symptoms of a soy allergy reaction
• Who can develop a soy allergy?
• How to prevent an allergic reaction to soy
• What to do if you’re having an allergic reaction to soy
• How to diagnose a soy allergy
• IgE food allergy testing at home
• Related content

Soy is a common ingredient that can provide many nutritious benefits to your body, from necessary proteins to amino acids and compounds that have been linked to improved health outcomes [1]. But if you have a food allergy to soy, you’re better off finding those nutrients from another source.

If your soy allergy is new to you, it can be tricky to identify the symptoms—or even know if a particular symptom comes from soy in the first place. It’s also essential to determine if you are allergic to soy or simply have a soy intolerance.

Fortunately, knowing what soy allergy symptoms may look like—and what foods can cause a reaction—can help. Once you’re familiar with soy allergy symptoms, you can determine if you need to talk to your healthcare provider to learn how to prevent future reactions.

4 symptoms of a soy allergy reaction

When the body reacts to soy, it’s a sign that the immune system has identified the proteins of this food as an invader [2]. In a reaction, the body produces an immune response to defend you—defenses that can result in the symptoms we know as an “allergic reaction.”

If you have an allergic reaction to soy, it may present as one or several different symptoms. As with any food intolerance or sensitivity, the type and severity of symptoms that present can vary considerably from person to person [3].

For example, a soy reaction may include mild symptoms like irritated skin or shortness of breath, or more severe, even life-threatening symptoms [3].

That said, there are specific signs that you can look out for if you think you may be reacting to soy [3]. The four most common kinds of soy allergy symptoms include:

1. Dermatological symptoms -Itchy skin, hives, and eczema rashes are all possible symptoms of a soy allergy [3].
2. Respiratory symptoms -After exposure to soy, an allergic person may experience shortness of breath, wheezing, or difficulty breathing [3].
3. Digestive symptoms -Additional symptoms of an allergic reaction can include digestive reactions such as nausea, vomiting, and diarrhea [3].
4. Severe symptoms -A soy allergy can also present as fainting, dizziness, or tingling of the lips, mouth, and throat. In severe cases, serious conditions like chest tightness and anaphylaxis can also develop [3].

In most cases, reactions occur very quickly after consuming the allergen. Depending on the severity of an allergy, you may experience allergic symptoms within a few minutes to a few hours after eating soy [3].

Who can develop a soy allergy?

Soy allergies are most common among small children under the age of two. According to some studies, about 0.4% of infants and children are allergic to soy [2]. In some cases, children who express soy allergies at very young ages can grow out of them [3].

However, it's also possible for a person to develop a soy allergy as an adult. In fact, in a 2019 food allergy study with over 40,000 participants, 45.4% of those who reported a soy allergy claimed to have developed it after they’d reached adulthood [4].

It’s important to understand that because soybeans are in the legume family, a soy allergy can sometimes indicate that you have an allergy to other legumes. For example, a study from 2010 found that up to 88% of participants with a soy allergy were also allergic to peanuts [5]. If you have peanut allergy symptoms, learn more about specific symptoms, how to cope, treatments, and testing.

How to prevent an allergic reaction to soy

Although some people may outgrow their soy allergy (usually young children), there is no cure [3]. That means restricting your diet to soy-free foods is the best way to prevent an allergic reaction.

To that end, the best way to keep your diet soy-free is to read the ingredient labels on any food you buy or consume.

Food and beverage products in the United States are regulated by the Food and Drug Administration, so any approved products that contain soy must advertise it on the label [6]. If a food contains soy, you’ll usually find it at the top of the ingredient list or with an allergen label that says “contains: soy.”

As a rich source of high-quality protein and a versatile food that can take on many different shapes, soy is an abundant product that’s available in its own various incarnations and as an additive to several common foods.

However, if you have a soy allergy, it's critical to know what specific foods to avoid.

Soy-based products to avoid

You’re probably most familiar with soy as the central ingredient in a range of soy products [1]. Products that feature soy as the main ingredient include:

• Soy milk
• Soy sauces
• Soybean oil
• Soy-based infant formulas
• Soy nuts

Because of its high nutritional value, soy is also often used to produce many animal product alternatives, from dairy-free soy cheeses to vegetarian products that use soy instead of animal meat [1].

Soy is also the main ingredient in tofu, a food product that’s made from dried soybeans that have been crushed, boiled, and pressed into block shapes.

Other foods containing soy

Additionally, soy is often present in a variety of everyday foods. This can make identifying soy-containing foods a challenge, but a quick look at the food label can usually help you do so efficiently.

Knowing common soy foods to watch for can also help you know when to be wary. Some foods that often contain soy include:

• Some breads and starches - Certain bread products, like crackers, pastries, and cakes, may contain soy if peanuts, peanut oil, or soy flour is among their ingredients. Some processed cereals may also contain soy [7].
• Some vegetable dishes - Aside from the soybean itself, other vegetables aren’t likely to contain any soy—even other legumes. Still, it’s important to note that vegetables prepared with soy sauces or breading that uses soy products may trigger an allergic reaction [7].
• Some beverages - Since soy milk is a popular milk substitute, some beverages like tea and coffee may contain soy [7]. Soy is also present in some fruit drink mixes, hot cocoa mixes, and malt beverages.
• Some commercial soups - If you have some canned soups in the pantry, it’s a good idea to check their labels. Some canned soups and processed food may also contain soy [7].
• Other products -Many butter and margarine substitutes contain soy, so be careful of those if you think you’re allergic. Additionally, certain salad dressings, sauces, soy oil, plant-based cheeses like soy-based cheese, and other condiments like soy sauce may also contain soy [7].

What to do if you’re having an allergic reaction to soy

If you think you’re having an allergic reaction to soy, the best action you can take is to contact your healthcare provider right away. They can help guide you with the appropriate care, depending on the severity of the reaction.

That said, there are treatments that can help when you’re having an allergic reaction. They include:

• Antihistamines - In some cases, your healthcare provider may prescribe antihistamines that help to alleviate your soy allergy symptoms [3].
• Epinephrine -This vital adrenaline acts quickly to relieve the effects of anaphylaxis caused by an allergic reaction. Epinephrine can be easily administered using an auto-inject pen, but the medication is available by prescription only [3]. If you have a severe soy allergy, your healthcare provider may recommend keeping epinephrine on hand in case of a severe allergic reaction.

How to diagnose a soy allergy

If you think you or a loved one may have a soy allergy, it’s crucial to find out as soon as possible. Even if your allergy has only presented only mild symptoms, reactions can increase in severity with each exposure.

If you’re wondering how to know if you have a food allergy to soy, fortunately, there are multiple allergy testing methods you can use to find out if you’re allergic to soy. The most common methods for testing for a soy allergy are:

• Blood tests - Your healthcare provider can draw a blood sample and test it for the presence of immunoglobulin E (IgE) antibodies [3]. Your body produces these antibodies in reaction to an allergen.
• A skin-prick test - This method involves applying a liquified soy protein to your skin and then pricking the skin, allowing the protein to enter the body [3]. An allergic reaction is indicated if a red bump appears within fifteen minutes.
• An oral food challenge - This test involves direct exposure to soy from eating a soy product [3]. This is usually conducted under a healthcare provider’s supervision, with medications and equipment to manage a reaction.

IgE food allergy testing at home

Try the Everlywell at-home Food Allergy Test to learn your IgE reactivity to common food allergens, including soy. If you receive test results indicating increased reactivity that may be connected with a food allergy, you will receive a call from a nurse to help with next steps.

Related content

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Dairy allergy vs. lactose intolerance

Peanut allergy symptoms explained

How to know if you have a food allergy

References

1. The Science of Soy: What Do We Really Know? Environmental Health Perspectives. URL. Accessed June 16, 2022.

2. Soy. Food Allergy Research & Education. URL. Accessed June 16, 2022.

3. Soy Allergy: Symptoms, Treatments, & Tests. Mayo Clinic. URL. Accessed June 16, 2022.

4. Prevalence and Severity of Food Allergies Among US Adults. JAMA Network Open. URL. Accessed June 16, 2022.

5. The natural history of soy allergy. The Journal of Allergy and Clinical Immunology. URL. Accessed June 16, 2022.

6. Soy Allergy. Asthma and Allergy Foundation of America. URL. Accessed June 16, 2022.

7. Soy Allergy Diet. Johns Hopkins Medicine. URL. Accessed June 16, 2022.

8. Soy Foods & Soy Protein. Cleveland Clinic. URL. Accessed June 16, 2022.