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Drug Allergy

What is a drug allergy?

A drug allergy is a reaction by your child’s immune system to a medicine your child has taken. The immune system is the body’s defense against infection. Sometimes, the immune system reacts to something other than an infection. This is how allergic reactions happen. If your child is allergic to a medicine, even a small amount can trigger a reaction. The reaction can range from mild to life-threatening.

What is the cause?

When your child has an allergic reaction to a medicine, his immune system treats the drug as a foreign substance and tries to protect him from it. Any medicine can cause an allergic reaction. The medicines most likely to cause allergic reactions are:

  • Antibiotics, such as penicillin
  • Anti-seizure medicines
  • Aspirin and non-steroidal anti-inflammatory drugs (NSAIDS) such as Advil, Motrin or Aleve
  • Contrast dyes used for some X-rays
  • Some heart and cancer drugs
  • Local anesthetics (pain medicines), such as lidocaine or novocaine
  • Sulfa drugs

What are the symptoms?

The most common symptoms are:

  • Itching
  • Hives (a red skin rash)
  • Swelling of the lips, mouth, or skin

Symptoms of a drug allergy can happen within minutes or within a few days after your child starts taking the medicine. In some cases, it may be a week before your child has symptoms. Most symptoms go away 3 to 5 days after your child stops taking the drug.

Anaphylaxis is a life-threatening allergic reaction. The reaction is sudden and severe and involves the whole body. Symptoms of a severe reaction may include:

  • Rash or hives
  • Swelling or itching of the lips, face, or throat
  • Trouble swallowing
  • Trouble breathing, often with wheezing
  • Lightheadedness
  • Fast or pounding heartbeat
  • Nausea, vomiting, or diarrhea
  • Fainting
  • Feeling very nervous or confused

How is it diagnosed?

Your child’s healthcare provider will ask about your child’s symptoms and medical history and examine your child. Tell your child’s provider about all of the medicines your child is taking. This includes prescription and nonprescription drugs, supplements, natural remedies, herbs, and vitamins.

If your child has a severe allergic reaction he may need to see an allergy specialist for evaluation and tests.

How is it treated?

Several kinds of medicines may be used to treat allergies:

  • Antihistamines block the effect of histamine and help reduce your child's symptoms. Histamine is a chemical the body makes when your child has an allergic reaction. Do not give antihistamines to children under the age of 4 unless your child’s provider tells you to do so. If your child is between the ages of 4 and 6, ask your healthcare provider before giving antihistamines.
  • Steroid pills help reduce the irritation and swelling in the body. By lessening the swelling, your child will have fewer symptoms and be able to breathe better. Give steroid medicine exactly as your healthcare provider prescribes. Don’t give more or less of it than prescribed by your provider and don’t give it longer than prescribed. Your child should not stop taking a steroid without your provider's approval. You may need to lower the dosage slowly before your child stops taking it.
  • A severe allergic reaction is life-threatening and needs to be treated with a shot of epinephrine. Epinephrine relaxes the muscles in the airways, reduces swelling, and helps keep blood pressure from getting too low. Your child may be kept in the emergency room for a while to make sure the treatment stops the allergic reaction. Sometimes a reaction may be so severe that your child will need to stay in the hospital for a while to make sure the swelling, his breathing, and his blood pressure all go back to normal.

How can I take care of my child?

  • Follow your healthcare provider's instructions if your child was given medicine to take at home.
  • If your child had a severe reaction, his provider may prescribe an epinephrine emergency kit, such as EpiPen or Twinject. You will need to carry the kit with you at all times for younger children. Make sure his daycare or school also has a kit and knows how to use it. Older children will need to carry this kit with them at all times. It contains a ready-to-use syringe of epinephrine. If your child has a severe allergic reaction, a shot of this medicine can counteract allergy symptoms until emergency medical care is available. Your child or someone with him can give the shot and call 911 or emergency medical services.
    • You should check the expiration date for this medicine and replace it as needed to make sure it will work. It should not be stored at extreme heat or cold or in direct sunlight.
    • Sometimes 1 dose of epinephrine is not enough, so you may need more than 1 epinephrine pen for your child. If so, follow your healthcare provider’s instructions.
    • Ask your healthcare provider or pharmacist if you have any questions about safe use for your child.
  • Make sure your child wears a bracelet or necklace that warns of his allergy and tells what to do in case of an emergency. Tell your child’s family, friends, and teachers what they should do if your child has a severe reaction.

How can I help prevent allergic reactions?

  • Make sure that your child avoids taking medicine that caused the allergic reaction. Check medicine labels for the names of drugs your child is allergic to before he takes any medicine or natural remedy. A medicine may be available in different shapes and colors. Don’t depend on how a medicine looks to know whether it’s the one your child is allergic to. If you have questions, ask your provider or pharmacist.
  • Write down the name of any medicines your child has reacted to and what the reaction was. Carry this information with you.
  • Tell all healthcare providers who treat your child, including pharmacists and dentists, about all known allergies your child has.
Developed by RelayHealth.
Pediatric Advisor 2015.3 published by RelayHealth.
Last modified: 2014-10-15
Last reviewed: 2014-10-15
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
Copyright ©1986-2015 McKesson Corporation and/or one of its subsidiaries. All rights reserved.
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