Do You Have a Penicillin Allergy?

Many people think that they are “allergic” to penicillin, when they may not really be truly allergic.

Penicillin is a very effective and relatively inexpensive antibiotic, used in the treatment of many bacterial infections.  About 1 in 10, 000 people who receive penicillin may have a true allergic reaction, where the immune system considers the antibiotic as a harmful foreign agent and mounts a defensive attack.  The chemical mediators that are released during this process can cause itchy rashes, hives, and/or swelling of the tissues.  In rare cases, life threatening reactions can occur in which difficulty in breathing (i.e., wheezing, shortness of breath), cardiovascular manifestations (i.e., drop in blood pressure, shock) and other serious organ system damage can ensue.

However, two recent studies proved that most people who consider themselves allergic to penicillin can safely receive penicillin.  In one study, 94 percent of 384 people who believed they were allergic to penicillin tested negative for penicillin allergy.  In the second study, penicillin skin testing was performed on 38 people who believed they were allergic to the antibiotic, and all of them tested negative.

Most people with a presumptive history of sensitivity to penicillin are given alternate antibiotics to treat infections.  In some instances, the replacement antibiotic may not be as effective as the preferred penicillin and in addition, the substitute antibiotic is also more expensive.  Such use may also result in some bacteria developing resistance to antibiotics, harming the community at large.  Hence it is important to distinguish between false and true allergy to penicillin and related antibiotics.

A standardized skin testing procedure can differentiate people who are likely to adversely react to penicillin from those who can safely tolerate it.  It involves injecting small amounts of chemical determinants (reagents) of penicillin sensitivity into the layers of the skin, with appropriate positive and negative controls.  A positive test manifests as an itchy, red, raised bump after 15 minutes and confirms true allergy to penicillin and the need to permanently avoid penicillin and related antibiotics.

If the skin test is negative, a related drug, amoxicillin is given by mouth at a standard dose and the person is monitored in a board certified allergist’s office for 1 to 2 hours for any adverse reactions.  If the oral dose is also tolerated, he/she can safely receive penicillin and related antibiotics to treat infections in the future.

The board certified allergists at Black & Kletz Allergy can administer the penicillin skin testing and oral challenge, if needed, and can offer recommendations for appropriate antibiotic use based on the test results.  Please call any of our 3 offices in the Washington, DC, Northern Virginia, and Maryland metropolitan area with questions or concerns related to antibiotic or other medication allergies.  We have office locations in Washington, DC, McLean, VA (Tysons Corner, VA), and Manassas, VA and have been serving this area for more than 50 years.  There is parking at each one of our 3 office locations.  In addition, the Washington, DC and McLean, VA offices are also accessible by the Metro.  If you have wondered if your “penicillin allergy” was correct, please call us today or click Request an Appointment and we will contact you within 24 hours of the next business day.  We would be happy to test you for a penicillin allergy, so that you can clarify if you are truly allergic to penicillin.