Penicillin Testing

Penicillin testing is very similar to general allergy skin testing. We start with few skin prick tests using penicillin metabolites on your forearm. If necessary, intradermal testing is done next.  Finally, if your physician thinks it is safe, you will take a test dose of a penicillin containing medication to confirm that you are not allergic to penicillins. As such, penicillin testing, including taking a test dose and observation period afterwards, takes about 3 hours total.

Medications that Interfere with Allergy Skin Testing:

These medications interfere with allergy skin tests and SHOULD BE DISCONTINUED PRIOR TO TESTING:


Five days prior to testing, stop all over-the-counter allergy, cold and sleep medications (Allegra, Benadryl, Claritin, Clortrimeton, diphenhydramine, Zyrtec, etc.), and prescription antihistamines (Clarinex, Xyzal, etc.). This includes nasal sprays containing antihistamines, such as azelastine, Astepro, Dymista and Patanase.


  • Older antidepressants like Elavil (amitryptyline) should be stopped three days prior to testing.
  • Newer antidepressants (Prozac, Zoloft, etc.) do not interfere with testing.

Most medications do not interfere with skin testing and may be continued.

Do Not Stop The Following:

  • Cortisone nasal sprays (fluticasone, Nasonex, Nasacort AQ, Rhinocort, Veramyst, etc.)
  • Asthma medications (Albuterol, Flovent, Singulair, Advair, etc.)
  • Antibiotics
  • Eye drops for allergy (Patanol, Elestat, Zaditor, etc.)
  • Decongestants (Sudafed, Sudafed PE, etc.)
  • Oral steroids (Prednisone, Medrol, Prelone, etc.)
  • Birth control pills
  • Medicines for other conditions such as diabetes, arthritis, reflux, high blood pressure, etc.

We Do Not Perform Skin Testing on the Following Patients:

  • Women should not be skin tested if they are or may be pregnant
  • Patients taking beta blocker medications on a daily basis should not be skin tested or take allergy shots.

The use of beta blocker medications (which may be prescribed for high blood pressure, heart conditions, glaucoma, migraine prevention, etc.) may hinder the effectiveness of treating systemic reactions to allergy skin testing or immunotherapy. We will be unable to skin test patients who have been prescribed beta blocker medications, but these patients are eligible for allergy blood tests. Ask your pharmacist, prescribing physician or one of our nurses if you are not sure if your medication is a beta blocker. Discover More about Beta Blockers.