Version July 2025
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What is a soy allergy? —
A food allergy is when the immune system acts like a certain food is harmful to the body. The immune system is the body's infection-fighting system.
Some people are allergic to soybeans, or "soy." This includes foods made with soy. Soy allergy is more common in babies and young children.
Most often, allergic reactions happen from eating the food or something that contains the food. Touching the food can also cause a skin reaction.
What are the symptoms of an allergic reaction? —
With "classic" food allergies, also called "IgE-mediated" food allergies, common symptoms include:
●Hives, which are raised or puffy areas of skin that are itchy (picture 1 and picture 2)
●Flushing
●Swelling, especially of the face, eyelids, or lips (picture 3 and picture 4)
●Trouble breathing, noisy breathing (wheezing), or coughing
●Nausea, vomiting, or diarrhea
●Feeling dizzy or passing out
●Looking sick, seeming sleepier than usual, or not acting normally (in babies and young children)
The above symptoms often start quickly, usually minutes to 1 hour after having soy.
When an allergic reaction is more severe, it is called "anaphylaxis." This can make you very sick, very quickly. If not treated, it can lead to death. But this is rare.
Symptoms can differ from person to person. Also, a person can have different symptoms each time they have an allergic reaction.
There are other types of food allergies that cause different symptoms. These are called "non-IgE-mediated" food allergies. They include:
●Eczema – This is a skin condition that makes the skin itchy, flaky, and change color (for example, get redder, darker, or lighter).
●Eosinophilic esophagitis – This is a condition that makes it hard to swallow food. It can also cause heartburn that does not get better with the usual treatments.
●Food protein-induced enterocolitis syndrome ("FPIES") – This is a condition that is usually caused by milk (for example, in baby formula). It can also be caused by soy. It mostly affects children, and causes severe vomiting and diarrhea.
●Food protein-induced allergic proctocolitis ("FPIAP") – This is a milder condition than FPIES. It can cause diarrhea with blood or mucus in babies.
Is there a test for a soy allergy? —
Yes. Your doctor or nurse will ask about your symptoms. You might need to see an allergy specialist, called an "allergist."
Your doctor can order tests such as:
●Blood test – This looks for proteins that the body makes when it is having an allergic response to soy. These proteins are called "IgE antibodies."
●Skin test – This involves pricking your skin with a device that contains a tiny amount of soy. If you get a red, itchy bump, like a mosquito bite, it means you are allergic to soy.
If the doctor still cannot tell if you or your child has a soy allergy, they might order a test called an "oral food challenge." This involves eating a small serving of the food and gradually eating more to see if it causes symptoms. For safety reasons, this is only done in a doctor's office or hospital.
Can a soy allergy be cured? —
As of now, there is no cure for a soy allergy.
But there are treatments that might help. These include omalizumab (brand name: Xolair). This medicine comes as a shot. You start treatment in a clinic or hospital, where you can be monitored and treated if you have a reaction. Then, you get a shot every 4 weeks. After your first shot, you might be able to give yourself the rest of the shots at home. Getting treatment regularly might make you less likely to have a reaction if you are accidentally exposed to soy.
Omalizumab comes with risks. It is not likely to make an allergy go away completely, and most people need to continue to avoid soy. But it might be an option in certain situations. If you want to learn more, talk with your doctor or nurse.
How are allergic reactions treated? —
Severe allergic reactions are treated with medicine called epinephrine. Ambulance crews and doctors can give it. People who had anaphylaxis before often get a prescription for epinephrine. It comes in 2 forms:
●A device called an "autoinjector" (sample brand names: Auvi-Q, EpiPen), which is a shot you can give yourself (figure 1)
●A spray that goes in the nose (brand name: neffy) (figure 2)
If your doctor prescribes epinephrine:
●They will show you how to use it.
●They will give you instructions for when to use it.
●Keep it with you at all times. Most doctors recommend carrying 2 doses in case you need a second dose. You might need a second dose if:
•Your symptoms do not go away completely.
•Your symptoms go away, but then start to come back.
•You used an autoinjector that did not work correctly the first time.
Call for an ambulance (in the US and Canada, call 9-1-1):
●After you use epinephrine – The medicine does not last very long in the body. Symptoms can sometimes come back as the medicine wears off. In the hospital, doctors can watch you and give you more medicine if needed.
●If you think someone is having anaphylaxis, and you do not have epinephrine
Your doctor might also recommend an antihistamine, such as cetirizine (sample brand name: Zyrtec). You can get these without a prescription. They can help relieve mild food allergy symptoms like itching and hives. They do not treat anaphylaxis.
How can I prevent an allergic reaction? —
The best way to prevent is to completely avoid soy and products that contain soy. Even a tiny bite that contains the food can cause a big reaction.
●To know whether a food contains soy, read its ingredient label. Some countries (including the US) have laws that make companies clearly list whether a food has certain common "allergens" in it. These include soy.
●Some foods have warning labels for food allergies, such as "May contain soybeans." These might have been made on machines or in factories that are also used for other foods that contain soy. Talk to your doctor about whether you should avoid these foods.
●If you eat at a restaurant, bakery, or ice cream shop, tell your server about your allergy.
●Non-food items can also have soy in them. These include medicines, vaccines, cosmetics, and craft supplies. Most countries (including the US) do not have laws that make companies list if these items have potential allergens in them. If you think you are allergic to any non-food items, talk to your doctor about ways to avoid them.
What else should I know if I have a soy allergy? —
People with a soy allergy:
●Can have an allergic reaction if they share saliva with (kiss) someone who ate soy and did not brush their teeth after
●Can get hives on their skin if they touch soy
●Could have an allergic reaction by breathing in tiny droplets of soy – This can happen when cooking with soy or when soy milk is steamed for coffee.
●Are usually not allergic to other legumes, such as peanuts or beans
●Can wear a medical alert bracelet or necklace to tell others about their soy allergy – If you cannot wear a bracelet or necklace, you can carry a document called an "allergy passport" or "allergy card."
Some people have allergies to more than 1 food. If you have other food allergies, you need to avoid those foods, too.
Your doctor or nurse might have you work with a dietitian (food/nutrition expert). They can help you learn how to:
●Avoid the food you are allergic to
●Use other foods in place of the food you are allergic to
●Make sure you get the nutrients you need
What if my child has a soy allergy? —
Tell their caregivers, schools, and camps. You should:
●Tell them which foods your child can and cannot eat.
●Make a plan so they know how to treat an allergic reaction.
●Make sure they know where your child's epinephrine is, and how and when to use it.
●Make sure they know how to reach you or your child's doctor in case of an emergency.
Will my child grow out of their soy allergy? —
Most children grow out of their soy allergy. Your child's doctor will monitor your child's allergy over time to see whether they outgrow it.
Where can I learn more? —
You can get more information about food allergies from Food Allergy Research & Education ("FARE") at www.foodallergy.org.
Patient education: Food allergy (The Basics)
Patient education: Hives (The Basics)
Patient education: Angioedema (The Basics)
Patient education: Anaphylaxis (The Basics)
Patient education: How to give epinephrine (The Basics)
Patient education: Allergy skin testing (The Basics)
Patient education: Eczema (atopic dermatitis) (The Basics)
Patient education: Eosinophilic esophagitis (The Basics)
Patient education: Food allergy symptoms and diagnosis (Beyond the Basics)
Patient education: Food allergen avoidance (Beyond the Basics)
Patient education: Hives (urticaria) (Beyond the Basics)
Patient education: Anaphylaxis symptoms and diagnosis (Beyond the Basics)
Patient education: Anaphylaxis treatment and prevention of recurrences (Beyond the Basics)
Patient education: Using an epinephrine autoinjector (Beyond the Basics)
Patient education: Eczema (atopic dermatitis) (Beyond the Basics)
