Symptoms of Allergic Reactions

Is my baby having an allergic reaction?

Allergic reactions to food typically occur within two hours of consuming the allergenic food—and often just minutes.1 The more of the allergen consumed, the more severe the reaction is likely to be, so it is important to start small when introducing new foods to your baby. Lastly, your baby may not have an allergic reaction the first time they are exposed to the food, so be watchful on the second and subsequent exposures. 

If you think your baby is having an allergic reaction, call 9-1-1 immediately.

Symptoms of an allergic reaction vary from baby to baby, and can range from mild to severe. Generally, the severity of a reaction is judged by how many symptoms are present and the severity of those symptoms. Before you introduce potential allergens into your baby’s diet, know how to recognize the signs of an allergic reaction.

Common symptoms of an allergic reaction are described below.2

Symptoms of mild allergic reactions:

Mild symptoms of an allergic reaction can include ONE of the following (more than one would constitute a more severe reaction):

  • Itchy or runny nose, sneezing
  • Itchy mouth
  • A few isolated hives, mild itching
  • Mild nausea or gastrointestinal discomfort

If you note any of the above symptoms, stop feeding the allergen and contact your pediatrician, family practitioner, or allergist for guidance. If your child is having multiple symptoms, call 9-1-1 immediately and request an ambulance with autoinjectable epinephrine.

Symptoms of severe allergic reactions in babies:

More severe reactions may include any of the following, either alone or in combination:

  • Shortness of breath, wheezing, repetitive cough
  • Pale or bluish skin
  • Swelling of face, lips, or tongue
  • Widespread hives on body
  • Repetitive vomiting
  • Sudden tiredness/lethargy/seeming limp

If your child is having any of the above symptoms, call 9-1-1 immediately and request an ambulance with autoinjectable epinephrine. Do not wait.

Delayed Symptoms & FPIES

FPIES (Food Protein-Induced Enterocolitis Syndrome) is a type of food allergy in children that can be severe and life- threatening. Unlike most allergic reactions (which can occur within minutes), FPIES allergic reactions occur within hours after consuming a particular food. For this reason, FPIES is sometimes known as a delayed food allergy. Symptoms of FPIES can include vomiting 1-4 hours and experiencing diarrhea 5-10 hours after ingestion of a specific food. Other symptoms include low blood pressure, low body temperature, extreme pallor, repetitive vomiting, and significant dehydration. If your child has been diagnosed with FPIES, they must be followed closely by an allergist or immunologist.

Critical information for caregivers

Should you or your baby’s caregiver ever need to call 9-1-1, things will move more quickly if you have the information below ready at-hand (this info is a good to put in your own iphone and on your refrigerator/wall for caregivers):

  • Birth date
  • Weight
  • Address
  • Insurance card (photo of, copy of)
  • Nearest hospital (or preferred hospital)
  • Special health info (e.g., baby was born prematurely at 30 weeks, etc.)

Reviewed by:

Sakina Bajowala, MD, FAAAAI. Board-Certified Allergist & Immunologist (allergy section)

  1. FARE, Common Questions. [website]. (Retrieved March 3, 2020
  2. FARE, Treating Severe Allergic Reactions. [website]. (retrieved March 3, 2020)