Soy allergy is a common allergy in infants and young children, and 20 percent of children with cow's milk allergy are also allergic to soy, notes the Australasian Society of Clinical Immunology and Allergy. Soy allergy is hard to avoid because soy is a major ingredient in many processed foods and natural flavorings and is an alternative to meat and cow's milk. A study of the natural history of soy allergy and predictors of oral tolerance/outgrowing soy allergy published in the March 2010 issue of "Journal of Allergy and Clinical Immunology" found that about 69 percent of the subjects outgrew their allergies to soy by age 10.
Skin Symptoms
Babies allergic to soy may experience symptoms related to skin allergies, such as hives, swelling and eczema, according to the "Journal of Allergy and Clinical Immunology." Initial symptoms may include a tingling sensation in the mouth and swelling of the lips, so a baby may become fussy and irritable upon immediate exposure to soy-based food or soy milk. Red, itchy, swollen bumps called hives may appear around the face and other parts of the body. Babies may also develop eczema, which is a red, itchy, scaly rash appearing on the cheeks, mouth, and sometimes the scalp and back of hands.
Nasal Symptoms
Hay fever may develop in infants allergic to soy. Babies may experience runny nose, nasal congestion, itchy nose and itchy, watery eyes. Infants who constantly pull on their ears may be showing signs of clogged or infected ears. Dark circles or puffiness under the eyes is another sign of hay fever in babies.
Digestive Symptoms
Infants allergic to soy may also experience abdominal pain, diarrhea, nausea or vomiting as a way to get rid of the offensive food in their digestive systems. A swollen tongue and throat may be signs of more extensive swelling inside the digestive and respiratory tract. It is important to seek immediate medical attention as swelling may block the airways.
Asthma Symptoms
Soy allergies can cause an asthma attack in babies who have been diagnosed with asthma. Symptoms include coughing, wheezing when breathing out, difficulty breathing and shortness of breath. Asthma in infants is difficult to diagnose because there may be more than one cause, and an infant's airways are not fully developed. An allergist with specialized training will help determine the exact cause and develop a treatment plan.
