The incidence of food allergy symptoms increases once your baby expands his food intake to include more than just milk, although milk is one of the most common food allergens. By 9 months, most babies have started eating solid foods, including table foods. Food allergy symptoms in babies can vary, so you may not recognize a symptom as an allergy, and your baby can't tell you how he feels. Once you recognize that your baby has an allergy, figuring out what he's allergic to can take time and detective work.
Skin reactions are the most common symptom of food allergy. Skin reactions can occur as a chronic condition, such as eczema, or as an acute reaction, such as hives or rash. Acute reactions often appear within minutes to a few hours after ingestion. Hives -- raised welts that move from area to area -- can occur anywhere on your baby's body. Swelling can occur around the eyes, mouth or lips. Eczema often affects babies with allergies and lasts beyond the initial allergic reaction. The itchy, often scaly, rough or bumpy patches of eczema often affect the face, especially the cheeks, forehead and scalp. In crawling infants, such as a 9-month-old, eczema often affects the elbows or knees.
Allergies in infants often affect the respiratory system. A 9-month-old might develop a runny or stuffy nose, sneezing, coughing or a more serious symptom, such as wheezing. A baby can't tell you he has chest tightness or shortness of breath. He may breathe faster than normal. Swelling around the baby's mouth or lips can lead to breathing difficulties if the throat and bronchial tubes also narrow. A baby with breathing problems needs immediate medical evaluation.
Gastrointestinal symptoms can be the hardest to recognize as part of an allergic reaction. Vomiting, abdominal cramping or diarrhea occur as part of viral illnesses as well as allergies. A 9-month-old may fuss, tense her abdominal muscles and draw up her legs or refuse to eat.
Most food allergy reactions infants are mild, but occasionally a severe reaction called anaphylaxis can occur -- even if your baby had only a mild reaction to a food previously. An anaphylactic reaction develops very quickly after your baby ingests an allergen. He might break out in hives and his face, lips and tongue can swell. His airway also can swell, even though you can't see it, and become blocked quickly. His blood pressure might drop and he might collapse. Anaphylaxis is a medical emergency. Call 911 immediately if your baby develops these symptoms.