Soy products manufactured from soybeans are a common source of food allergies, particularly in children. Many children outgrow soy allergies by age 3, however the allergies may persist into adulthood. The symptoms of an allergic reaction to soy are usually mild, although in rare cases, a severe, life-threatening reaction may occur. If you suspect you have a soy allergy, you should consult your doctor.
Anaphylaxis
In rare cases, a soy allergy can cause a severe reaction, known as anaphylaxis. During anaphylaxis, swelling may cause the airways to constrict, causing difficulty breathing. Shock may develop, resulting in a large drop in blood pressure and a weak, rapid pulse. The entire body may flush, feeling warm to the touch and taking on a reddish color. Lightheadedness and dizziness may also occur, as well as drooling and difficulty swallowing. Difficulty speaking and changes to voice quality are also possible. If you experience any of these symptoms, you should contact emergency medical services immediately.
Gastrointestinal
Gastrointestinal symptoms commonly result from allergies to soy, such as nausea and vomiting. Diarrhea may also occur, which may be accompanied by abdominal pain and cramping. Symptoms may develop within minutes of eating soy, or may not occur for up to an hour.
Swelling
Swelling is another common symptom of soy allergies. The face, lips, tongue and throat are common sites of swelling, but other body parts, such as the hands and feet, may swell as well. Swelling may be accompanied by itching, and hives or eczema may develop.
Additional Symptoms
Additional symptoms that may result from a soy allergy include a tingling sensation in the mouth. A runny nose may also develop. Even without full-blown anaphylaxis, an allergic reaction to soy may cause wheezing or difficulty breathing, as well as fainting or dizziness.
