General Allergic Reactions (Child)

An allergic reaction is a set of symptoms caused by an allergen. An allergen is something that causes your child's immune system to react abnormally and release various chemicals. These chemicals include histamine and many others. Histamine causes swelling and itching. An allergic reaction may affect the entire body. This is called a general allergic reaction. But often symptoms affect only a single part of the body. This is called a local allergic reaction.

Your child is having an allergic reaction. Almost anything can cause one. Different children are allergic to different things. It's usually something your child ate or swallowed, came into contact with by getting or putting it on their skin or clothes, or breathed in the air. The immune system for some children is very sensitive. A child can have an allergic reaction to many things. 

Common allergy symptoms include:

  • Itching of the eyes, nose, and roof of the mouth

  • Runny or stuffy nose

  • Watery eyes 

  • Sneezing or coughing 

  • A blocked feeling in the ears

  • Red, raised itchy rash called hives

  • Rash, redness, welts, blisters

  • Itching, burning, stinging, pain

  • Dry, flaky, cracking, scaly skin

  • Red and purple spots

Severe symptoms include:

  • Nausea and vomiting

  • Diarrhea

  • Swelling of the face, lips, throat, and mouth

  • Trouble breathing, wheezing, or gasping for breath

  • Lightheadedness, fainting, or dizziness

  • Cool, moist, pale skin

  • Fast but weak heartbeat

  • Feeling of doom

  • Stomach pain

If your child has severe symptoms, it's called anaphylaxis. This is a medical emergency, and you should call 911 right away.

An allergic reaction can be caused by many kinds of allergens. Common causes of local or mild to moderate allergic reactions are:

  • Pollen

  • Mold

  • Mildew

  • Animals

  • Dust

Severe allergic reactions can be caused by:

  • Foods, such as peanuts, eggs, shellfish, fish, soy, tree nuts, wheat, and milk

  • Medicines

  • Latex

  • Insects, especially bees, wasps, hornets, and yellow jackets

Mild symptoms often go away by using antihistamines or steroids. In some cases, pain medicine can help ease symptoms. Ask your child's healthcare provider what medicines are right for your child. But a child with a severe allergic reaction needs medical attention right away.

Home care

Woman giving liquid medication to boy.

The healthcare provider may prescribe medicines to relieve swelling, itching, and pain. Follow all instructions when giving these medicines to your child. If your child had a severe reaction, the provider may prescribe epinephrine. Epinephrine will help stop a severe allergic reaction and must be kept with the child at all times. Make sure that you understand when and how to use this medicine.

General care

  • Make sure your child does not scratch areas of their body that had a reaction. This will help prevent infection.

  • Help your child stay away from air pollution, tobacco and wood smoke, and cold temperatures. These can make allergy symptoms worse.

  • Try to find out what caused your child’s allergic reaction. Make sure to stay away from the allergen. Future reactions may be the same or might be worse.

  • If your child has a serious allergy, have them wear a medical alert bracelet that notes this allergy. Or carry a medical alert card for your baby.

  • If the healthcare provider prescribes epinephrine, keep it with your child at all times.

  • Tell all care providers and school officials about your child’s allergy. Teach them how to use any prescribed medicine, including epinephrine.

  • Keep a record of allergies and symptoms, and when they occurred. This will help your provider treat your child over time.

Follow-up care

Follow up with your child’s healthcare provider. Your child may need to see an allergist. An allergist can help find the cause of an allergic reaction and give recommendations on how to prevent future reactions.

Call 911

Call 911 right away if any of these occur:

  • Trouble breathing, talking, or swallowing

  • Any change in level of alertness or unconsciousness

  • Cool, moist, or pale (or blue in color) skin 

  • Fast or weak heartbeat

  • Wheezing or feeling short of breath

  • Feeling lightheaded or confused

  • Very drowsy or trouble waking up

  • Swelling of the tongue, face, or lips

  • Drooling

  • Severe nausea or vomiting

  • Diarrhea

  • Seizure

  • Feeling of dizziness or weakness or a sudden drop in blood pressure

When to seek medical advice

Call your child's healthcare provider or get medical care right away if any of these occur:

  • Hives or a rash

  • Spreading areas of itching, redness, or swelling

  • Fever (see fever section below)

  • Symptoms that are new, continue, or happen more than once

  • Redness, swelling, pain, fluid or colored drainage at the affected site

Fever and children

Use a digital thermometer to check your child’s temperature. Don’t use a mercury thermometer. There are different kinds and uses of digital thermometers. They include:

  • Rectal. For children younger than 3 years, a rectal temperature is the most accurate.

  • Forehead (temporal). This works for children age 3 months and older. If a child under 3 months old has signs of illness, this can be used for a first pass. The healthcare provider may want to confirm with a rectal temperature.

  • Ear (tympanic). Ear temperatures are accurate after 6 months of age, but not before.

  • Armpit (axillary). This is the least reliable but may be used for a first pass to check a child of any age with signs of illness. The provider may want to confirm with a rectal temperature.

  • Mouth (oral). Don’t use a thermometer in your child’s mouth until they are at least 4 years old.

Use the rectal thermometer with care. Follow the product maker’s directions for correct use. Insert it gently. Label it and make sure it’s not used in the mouth. It may pass on germs from the stool. If you don’t feel OK using a rectal thermometer, ask the healthcare provider what type to use instead. When you talk with any healthcare provider about your child’s fever, tell them which type you used.

Below are guidelines to know if your young child has a fever. Your child’s healthcare provider may give you different numbers for your child. Follow your provider’s specific instructions.

Fever readings for a baby under 3 months old:

  • First, ask your child’s healthcare provider how you should take the temperature.

  • Rectal or forehead: 100.4°F (38°C) or higher

  • Armpit: 99°F (37.2°C) or higher

Fever readings for a child age 3 months to 36 months (3 years):

  • Rectal, forehead, or ear: 102°F (38.9°C) or higher

  • Armpit: 101°F (38.3°C) or higher

Call the healthcare provider in these cases:

  • Repeated temperature of 104°F (40°C) or higher in a child of any age

  • Fever of 100.4° F (38° C) or higher in baby younger than 3 months

  • Fever that lasts more than 24 hours in a child under age 2

  • Fever that lasts for 3 days in a child age 2 or older

Online Medical Reviewer: Daphne Pierce-Smith RN MSN
Date Last Reviewed: 11/1/2024
© 2000-2025 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.