Soy allergy is common in infants and young children, often appearing when a milk-allergic baby drinks a soy-based infant formula. A breast-fed baby may also experience symptoms of soy allergy once he starts eating solid foods with soy ingredients or if the mother consumes soy milk, tofu, tempeh, edamame or other soy products. Symptoms usually occur within minutes to hours of eating food containing soy.
Hives and Swelling
Symptoms of soy allergy may begin with a tingling sensation in the mouth within minutes of consuming soy; your baby may become fussy and refuse food. Her lips, face or tongue may swell, and red, itchy bumps called hives may appear randomly on the body. Persistent exposure to soy may also result in an eczema rash -- extremely itchy, dry patches on the cheeks, scalp and extremities, notes The Children's Physician Network.
Asthma
Some infants with soy allergy may experience symptoms related to asthma, such as wheezing and difficulty breathing. Wheezing is a whistling sound that occurs during breathing when the airways become inflamed and narrow. Your soy-allergic infant may cough and breathe more rapidly, causing the skin around the ribs or neck to pull in tightly.
Vomiting and Colic
Allergy-causing soy proteins in the digestive system can cause the esophagus, stomach and intestines to swell and produce mucus in infants with soy allergy. Your baby may experience stomach pain, diarrhea, nausea or vomiting within hours of exposure, notes MayoClinic.com. These symptoms can also cause the infant to become fussy and colicky for days.
Anaphylactic Shock
Some infants with soy allergy may experience anaphylaxis -- a severe, life-threatening reaction of two body systems. For example, an infant may experience wheezing and vomiting, or hives and coughing immediately after exposure. Other symptoms may include swelling of the throat and airways, gagging and difficulty breathing. Shock, severe drop in blood pressure, weak and rapid pulse or fainting may also occur with anaphylaxis, according to MayoClinic.com. Call 911 immediately if you suspect a severe allergic reaction in your infant.
