• HP Allergy and Asthma Specialists

National Penicillin Allergy Day

Are you REALLY allergic to Penicillin?


Penicillin is one of the most frequently used antibiotics in the world. The penicillin family includes over 15 chemically related medications such as amoxicillin, ampicillin, augmentin, methicillin. Approximately 10% of all people in the United States reports a history of penicillin allergy. However, 90-95% of people reporting a penicillin allergy are not really allergic to penicillin. There are many reasons people make be mistakenly labeled penicillin allergy:

(1) Penicillin allergy diminishes or resolves over several years, so one may not be allergic anymore. Approximately 80% of penicillin allergic patients lose their penicillin sensitivity over 10 years.

(2) Penicillin allergy was misdiagnosed. For example, many viruses can cause rashes. If the patient is on penicillin at the time the doctor cannot know if the rash was from the penicillin or from the illness itself.

(3) Another medication taken at the same time as penicillin may have caused the reaction.

(4) The patient or physician is reporting a penicillin allergy, when in fact the reaction is an adverse reaction and not a true allergy, such as diarrhea or upset stomach.

It is important to find out if you are penicillin allergy because patient labeled penicillin allergic are treated more frequently with broad-spectrum antibiotics which can result in


· Increased antibiotic resistance

· Higher medical/medication costs

· Increased days of hospitalization

· Compromised medical care

· Increased morbidity and mortality


Luckily, there is an allergy test for penicillin allergy. Skin testing to penicillin followed by an oral challenge is the most reliable method for evaluating true penicillin allergy. It is a safe, highly sensitive test. It involves skin testing first and if negative, is followed by giving an oral dose of penicillin or amoxicillin to confirm that it is safe to use this antibiotic. Blood testing for penicillin allergy is less sensitive and specific and thus is not an appropriate substitute for penicillin skin testing. It is best to undergo penicillin skin testing when you are well and not immediately requiring the antibiotic. Delaying testing until an emergency situation arises raises the risk of illness and death in addition to overall medical costs. It is important to know that just because a family member is allergic to penicillin does not mean you will be. There is no predictable genetic inheritance pattern to penicillin allergy. You do not need to avoid penicillin if a family member is allergic to penicillin or a drug in the penicillin family. If you have any questions regarding penicillin allergy, you can always call your local allergist today.