KidsMD Health Topics

Antibiotic Allergy Testing

  • As many as 10 percent of children are allergic to antibiotics. If your child has had an allergic reaction to an antibiotic, a doctor may advise an allergy test for antibiotics.

    Skin testing is available for penicillin. Skin testing for other antibiotics, such as cephalosporins, can be done, but the validity is uncertain. Routine skin testing for sulfa drugs (found in Bactrim or Septra), erythromycin or clindamycin isn’t currently available.

    Contact Us

    Allergy and Asthma Program
    Boston Children's Hospital
    300 Longwood Avenue, Fegan 6
    Boston MA 02115 
    617-355-6117  888-IWHEEZE 

  • Do I need to do anything to prepare my child for the testing?

    Avoid prescription or over-the-counter antihistamines for one week before testing. Antihistamines will interfere with skin test results. Common products containing antihistamine include:

    • Actifed
    • Dimetapp
    • Pediacare cold formula
    • Triaminic cold formula
    • Benadryl
    • Claritin

    Patients on Hismanal should stop taking the medication at least six weeks before testing.

    If your child has a fever, or is having an increase in allergy or asthma symptoms, testing may need to be rescheduled. Call your doctor.

    What can I expect to happen at my child’s antibiotic allergy testing appointment?

    The appointment will take two to four hours. Much of the time will be spent waiting in between procedures. Feel free to bring a game, book or snacks. There are three or four stages of testing. With each advancing stage, an increasing concentration of antibiotic is used. If your child has a positive skin reaction to one of the components at any stage in the testing it isn’t necessary to test with that specific component any further.

    • Stage one: skin prick testing. 
      Several drops of liquid, including a histamine and saline control, are placed   on your child’s forearm with a device that has eight tiny points. Some children have described it as feeling like a hairbrush being lightly pressed onto the arm.

    • Subsequent stages: intradermal 
      In the next stages the antibiotic is placed under the top layer of skin on the back of the upper arm with the tip of a small needle.

    Occasionally local swelling and itching occurs at a skin test site four to eight hours after the testing. This isn’t serious and will disappear over the next several days.

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