14 Symptoms Of Soy Allergy In Babies, Risks, And Treatment

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Soy is a protein-rich legume capable of triggering allergies in babies (1). It is important to identify the symptoms of soy allergy in babies as early as possible. Soy proteins are treated as pathogens by the immune system of people with soy allergies. It releases antibodies (immunoglobulin E or IgE) to fight the allergen, leading to an allergic reaction (2). Soy should be introduced to babies only when they reach six months of age and above. You may start foods that may be possible allergens in small quantities one at a time. It helps in differentiating between the possible causes of food allergies. Keep reading the post about soy allergy symptoms, causes, and management options in babies for more information.

Symptoms Of Soy Allergy In Babies

A baby allergic to soy can show the following symptoms on the consumption of soy products (3).

  1. Vomiting
  2. Dizziness
  3. Confusion
  4. Watery eyes
  5. Stomach cramps
  6. Indigestion
  7. Diarrhea
  8. Wheezing
  9. Itchiness of the skin
  10. Hives
  11. Swelling of the tongue or lips
  12. Shortness of breath
  13. Repetitive cough
  14. Hoarse voice

According to the American College of Allergy, Asthma, and Immunology, a soy allergy can rarely cause an anaphylactic shock, where there is a sudden drop in blood pressure along with difficulty in breathing (3).

When To See A Doctor?

See a doctor immediately if the baby shows the following symptoms, which might indicate an anaphylactic reaction.

  1. The skin turning blue
  2. Difficulty in breathing
  3. Drooling or difficulty in swallowing
  4. Weak or extremely rapid pulse
  5. The body turning red and warm

Epinephrine (adrenaline) auto-injector can help relieve the conditions immediately. If your baby is confirmed to have a soy allergy, then the doctor may recommend you to keep an epinephrine auto-injector (epipen) handy.

Causes And Risk Factors Of Soy Allergy

It is not very clear as to why some people develop soy allergy. Research suggests that food allergy might be a result of a mix of genetic and environmental factors. Some factors increase the susceptibility to develop soy allergy (4).

  • The presence of other food allergies and allergic conditions like eczema, asthma, hay fever, etc., increase the risk.
  • Infants whose parents or siblings have soy allergy are more likely to have an allergy.

Soy allergy is one of the eight most common food allergies in the US (4). It is a part of the legume family, but a person allergic to soy need not be allergic to other legumes(3).

Diagnosis And Tests

There is no single method to identify the presence of soy allergy in babies. The doctor might employ the following methods (4).

  1. Elimination diet test: The doctor will suggest eliminating the suspected food item from the baby’s diet. For instance, if the baby consumes soy-based infant formula, then the doctor may suggest you to replace it with a standard formula. If the symptoms go away with no recurrence, then the doctor can conclude that the baby was allergic to soy. Elimination diet tests could involve multiple trials, thus it might take time to diagnose the allergy. However, this method is safe and non-invasive.
  1. Blood tests: It will check for the presence of food-specific antibodies in the blood to determine the presence of food allergy.

A skin prick test is performed in older children and adults to determine the presence of food allergies. The test involves injecting a small quantity of suspected allergen into the skin. If a bump develops at the spot of injection, then the allergy is confirmed.

This test may be risky for infants due to the required exposure to an allergen. Also, the bump at the site of injection can be uncomfortable. Therefore, the doctor might use a combination of elimination diet test and blood test to determine the presence of soy allergy in babies.

Treatment Of Soy Allergy

The treatment of soy allergy involves the management of anaphylactic shock and the long-term management of the allergy. The American Academy of Pediatrics enlists the following medicines to help in managing soy allergies in babies (5).

  1. Epinephrine: It is the first line of treatment. The doctor might suggest and train you on when and how to use the auto-injectable epinephrine for your baby’s allergy. There is no single universal dose of epinephrine. The amount of dosage required by the baby will depend on the intensity of their allergy and body weight. The pediatrician will recommend the exact dose and dosage.
  1. Antihistamines and corticosteroids: The doctor may suggest these medicines to treat mild cases, which do not require epinephrine.

If it is confirmed that your baby has a soy allergy, then they must avoid the following soy products for the long-term management of soy allergy (6).

  • Soy-based infant formula
  • Soy flour
  • Tofu
  • Soy milk and soy milk products, like soy milk yogurt
  • Soybean starch and oil
  • Cooked soybeans and soybean broth
  • Soy sauce and other fermented soy products

The following are some packaged products that might contain soy or soy derivatives.

  • Baked items like cookies, crackers, and cakes
  • Canned broths and soups
  • Cereals
  • High-protein energy bars and snacks
  • Peanut butter
  • Vegetable sauces
  • Soaps and moisturizers

It is good to check the ingredients mentioned on the label to determine the presence of soy. Stanford Children’s Health instructs parents to look for labels such as “processed in a facility that also processed soy” or “made on shared equipment” and check with their child’s doctor about the safety of such products. These foods may not contain soy but may have it as a contaminant during manufacturing (7).

Prevention Of Soy Allergy

It is difficult to prevent any food allergy. The following measures might help reduce the risk of soy allergy to a certain extent (8).

  1. Exclusively breastfeed the baby for the first four to six months, or use a hypoallergenic formula. Breast milk helps strengthen the immune system and might reduce the risk of allergies.
  1. Begin a solid diet at the age of six months by first introducing the baby to mild food items. Fruits like apples, pears, bananas, or vegetables like sweet potatoes, squash carrots or rice or oats may be introduced. Introduce one food item at a time and continue it for three to five days. It helps in identifying if the baby is allergic to any particular item.
  1. Highly allergic food items like soy, eggs, milk, peanuts, fish, etc., should be introduced only once you know that the baby tolerates mild food items well. It is good to consult a pediatrician before introducing foods that are considered allergic.
  1. If your baby has an allergy to another food, then consult a doctor before introducing soy. Discuss with the doctor about the quantity of soy that would be safe to introduce.

Soy allergies in babies could show symptoms such as lightheadedness, vomiting, stomach issues, skin changes, breathing difficulties, cough, etc. Though the exact cause is unknown, it could be caused due to environmental and genetic factors. Nevertheless, soy allergy could be managed by timely diagnosis and taking certain essential preventive measures. Moreover, a study conducted with 130 participants demonstrated that 50% of babies may outgrow this allergy by seven (1). However, if you notice your baby’s symptoms getting worse or developing new symptoms, it is best to seek medical care.

Infographic: Identifying Soy-Based Products

There are many products in which soy is the main or additional ingredient. If your baby has a soy allergy, it is crucial that you know these products and how to identify them. Find an infographic below that lists the products containing soy and a few tips on reading the product labels.

read the label and find the soy [infographic]
Illustration: MomJunction Design Team


MomJunction's articles are written after analyzing the research works of expert authors and institutions. Our references consist of resources established by authorities in their respective fields. You can learn more about the authenticity of the information we present in our editorial policy.
  1. Food allergies in babies and young children; NHS UK.
  2. Jacob D. Kattan, Renata R. Cocco, and Kirsi M. Jarvinen, Milk and Soy Allergy; Pediatric Clinics of North America.
  3. Soy Allergy; American College of Allergy, Asthma, and Immunology.
  4. WHAT CAUSES FOOD ALLERGIES?; Food Allergy Research & Education.
  5. Epinephrine for First-aid Management of Anaphylaxis; Official Journal of The American Academy of Pediatrics.
  6. SOY ALLERGY; Food Allergy Research & Education.
  7. Soy Allergy Diet for Children. Lucile Packard Children’s Hospital Stanford.
  8. PREVENTION OF ALLERGIES AND ASTHMA IN CHILDREN; American College of Allergy, Asthma, and Immunology.
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Dr. Ritika Shah

Dr. Ritika Shah is a certified lactation counsellor from iNational Health Care Academy, Singapore and a dental surgeon with more than seven years of clinical experience across various cities in India. She did her graduation in Dentistry from KM Shah Dental College. During her clinical practice, pediatric dentistry was her particular area of interest, and she constantly thrived to inculcate... more

Dr. Anuradha Bansal

Dr. Anuradha Bansal is a pediatrician and neonatologist working as assistant professor in the Department of Paediatrics at PIMS Jalandhar. She has done her MBBS and MD Pediatrics at GMCH, Chandigarh. Thereafter, she polished her skills as senior resident at MAMC, Delhi. She has also done IAP Fellowship in Neonatology at GMCH, Chandigarh and obtained the membership of the prestigious... more