Soy is considered one of the more common food allergens, along with proteins in milk, eggs, peanuts, nuts, fish, shellfish, and wheat. If you suspect any allergic reaction, immediately consult your health care provider before using/consuming the product. Like any of these allergens, soy is harmful to those who are allergic to it, but this has no bearing on its safety for the general population. In most cases, signs and symptoms of soy allergy are relatively mild, and it is relatively rare in adults. If you suspect a soy allergy, tests can help confirm any allergies so that steps can be taken to avoid future reactions. The Asthma and Allergy Foundation offers additional information on allergies that may be helpful.