Diagnosis

Your doctor will ask about your symptoms and may perform a physical exam. He or she may recommend one or both of the following tests:

  • Skin test. Your skin is pricked and exposed to small amounts of the proteins found in soy. If you're allergic, you develop a raised bump (hive) at the test site on your skin. Allergy specialists usually are best equipped to perform and interpret allergy skin tests.
  • Blood test. A blood test can measure your immune system's response to soy by measuring the amount of certain antibodies in your bloodstream, known as immunoglobulin E (IgE) antibodies.

Treatment

The only way to prevent an allergic reaction is to avoid soy and soy proteins.

Medications, such as antihistamines, may reduce signs and symptoms of soy allergies. Taking an antihistamine after exposure to soy may control your reaction and help relieve discomfort. Over-the-counter antihistamines include: diphenhydramine (Benadryl, others), chlorpheniramine (Chlor-Trimeton, others), cetirizine (Zyrtec, others) and loratadine (Alavert, Claritin, others).

Despite your best efforts, you can ingest soy unknowingly. If you have a serious allergic reaction, you may need an emergency injection of epinephrine and a trip to the emergency room.

Lifestyle and home remedies

If you're at risk of having a severe reaction or have had one:

  • Carry injectable epinephrine (EpiPen, Auvi-Q, others) with you always. Make sure you know when and how to use portable epinephrine.
  • Wear a medical alert bracelet to let others know about your allergy.

Preparing for your appointment

Call 911 or emergency medical help or go to an emergency room if you or your child develops symptoms of anaphylaxis, such as difficulty breathing or a rapid, weak pulse.

For less severe symptoms, call your family doctor or pediatrician. In some cases, you may be referred to a doctor who specializes in the diagnosis and treatment of allergic illness (allergist).

Here's some information to help you get ready and to know what to expect from your doctor.

What you can do

  • Write down symptoms you or your child has had and for how long. Also note if you or your child has had a similar reaction to other foods in the past. If you took photos during a previous reaction, bring those to show your doctor.
  • Make a list of key medical information, including other recent health problems and prescription and over-the-counter medications you or your child is taking. It will also help your doctor to know if you have a family history of allergies or asthma.
  • List recent dietary changes. Include as many details as you can about new foods you or your child has recently tried. Have you recently given your baby a new infant formula? Bring labels or ingredient lists from foods that concern you to the appointment.
  • Write down the questions to ask your doctor. This will help you make the most of your time together.

    Some questions to ask about soy allergy include:

    • Do these symptoms suggest a food allergy?
    • Do you think soy is the most likely cause?
    • Are there other possible causes?
    • How will you make the diagnosis?
    • How do I manage soy allergy?
    • What foods should I or my child avoid?
    • Should I or my child carry an epinephrine auto-injector?
    • Is it necessary to wear a medical alert bracelet?
    • Does soy allergy increase my or my child's risk of other food allergies?

    If your child is the one with symptoms, ask your doctor these additional questions:

    • What adults should know about this allergy to help keep my child safe?
    • Do you expect my child will outgrow soy allergy?
    • Are my other children at increased risk of soy allergy? If yes, are there preventive steps I can take?

    Don't hesitate to ask other questions, as well.

What to expect from your doctor

Your doctor is likely to ask you a number of questions, including:

  • What symptoms have you or your child been having?
  • When did symptoms begin?
  • How soon after eating a particular food do symptoms appear?
  • Do symptoms seem to be getting worse?
  • Have you or your child recently added new foods to your diet?
  • Are you or your child allergic to other foods?
  • Do you have a family history of allergies or asthma?
  • Are you or your child being treated for other medical conditions?

If your baby or child is the one with symptoms, your doctor also may ask:

  • Have you recently started using a new infant formula?
  • Do you or did you breast-feed your child? For how long?
  • Has your child recently started eating solid foods?
  • What foods do you typically include in your family diet?

What you can do in the meantime

Symptoms of soy allergy in babies may appear when a baby starts a soy-based infant formula. If you suspect your baby is allergic to soy, reduce exposure to allergens by feeding him or her breast milk. If your baby is eating solid foods, avoid products with soy.

If you're not nursing, ask your doctor for advice on what to feed your child until your appointment to reduce the risk of symptoms.

If you have symptoms of soy allergy, avoid foods that contain soy.

July 11, 2014
References
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  3. Soy allergy. Asthma and Allergy Foundation of America. https://www.aafa.org/display.cfm?id=9&sub=20&cont=522. Accessed March 26, 2014.
  4. Savage JH, et al. The natural history of soy allergy. Journal of Allergy and Clinical Immunology. 2010;6:125.
  5. Masilamani M, et al. Determinants of food allergy. Immunology and Allergy Clinics of North America. 2012;32:11.
  6. Burks W. Diagnostic evaluation of food allergy. http://www.uptodate.com/home. Accessed March 26, 2014.
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