Signs and Symptoms of a Soy Allergy

If you are allergic to soy and are avoiding it, get in the habit of reading the labels on your favorite baked goods, cereals, crackers, soups, infant formula and even peanut butter. Many products these days contain soy protein and flavoring additives. At least 15 allergens are present in soy protein, yet it is still not known exactly how soy protein triggers an allergic reaction. Today soy allergies are becoming more and more common in adults.

Common Signs and Symptoms

• Soy beans and peanuts are in the same family.

  Allergic reactions to soy may begin within minutes or hours of ingesting soy. Most reactions may be uncomfortable but not serious. Reactions vary and may include one or more of the following signs and symptoms: eczema, acne, hives, stomach pain, nausea or vomiting, shortness of breath, runny nose, chest tightness, breathing difficulties, diarrhea, dizziness, fainting, itching, lethargy and swelling. The allergic reaction to soy may also produce a tingling of the lips or face, throat or tongue or even conjunctivitis, commonly known as pink eye. A reaction to a soy product can last as long as 48 hours. Since the soybean is a legume, if you have a soy allergy you may cross-react to other legumes, such as peanuts, garbanzo beans and string beans.

More Serious Signs and Symptoms

• A systemic allergic reaction, called anaphylaxis, can come on suddenly and affect areas throughout the body. This type of reaction, while rare, can be potentially fatal. Emergency treatment should be sought immediately. Aspects of this severe reaction include rapid pulse, a sudden drop in blood pressure, drooling, swelling or a lump in the throat that makes breathing or swallowing extremely difficult, the presence of a metallic taste, hoarseness, redness and flushing of the body, dizziness and possible loss of consciousness.

Allergic Reactions to Soy in Infants

• According to an article in the June 15, 2008 issue of "American Family Physician," 90 percent of acute systemic food reactions in children are caused by milk, eggs, soy, peanuts or wheat. Infants and young children with soy allergies usually outgrow them between the ages of three and five. The first sign of a soy allergy reaction in an infant may begin when a change is made from a milk-based formula to a soy-based one. These allergic reactions include blood in the stool, delayed growth and colic. To complicate the detection of soy allergy in infants and young children, the signs of allergic reaction to soy and to milk can be very similar and may also resemble other health problems.