Symptoms of a soy allergy may include abdominal pain, tingling in the mouth, wheezing, swelling of the throat or facial area, skin redness, itching and hives, as listed by Mayo Clinic. Symptoms of anaphylaxis, a more severe allergic reaction, include dizziness, difficulty breathing, rapid pulse and shock.
Affected individuals may also experience a runny nose, breathing difficulty, eczema, diarrhea, nausea and vomiting, according to Mayo Clinic. Swelling often affects the tongue, throat or lips, but it may impact other body parts. Symptoms generally appear several minutes to several hours after the individual consumes the allergen, and they are rarely severe. Individuals should consult an allergist if they experience these symptoms soon after eating. If they are diagnosed with a soy allergy, they should avoid soy products and read labels to avoid soy ingredients in unexpected food items, such as meats and peanut butter.
Although anaphylaxis rarely accompanies soy allergies, patients have an increased risk of a severe reaction if they have asthma or allergies to other foods, as confirmed by Mayo Clinic. Serious throat swelling may constrict breathing, and a rapid drop in blood pressure may accompany shock. Additional symptoms include lightheadedness, drooling, the inability to swallow and a loss of consciousness. The patient may also experience warmth and redness that affects the whole body. Anaphylaxis can be life threatening and requires emergency medical attention.