Study Examines Penicillin Allergies

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Study

Examines Penicillin Allergies

April 29, 2004

PHILADELPHIA (AP) -- A study by University of Pennsylvania researchers casts doubt on the conventional wisdom that

most penicillin allergies are forever.

The researchers found that the number of

people who had an allergic symptom after taking penicillin and then had

another episode after taking the antibiotic again was far fewer than

expected.

However, the researchers stressed that more

study is needed before doctors start writing

penicillin prescriptions for patients who say they're allergic.

Previous smaller studies had concluded that

about 60 percent of people who have an allergic reaction once to penicillin

will have another one if they take the antibiotic again. However, the Penn

researchers' review of 3.4 million electronic medical records for people in Great Britain who were prescribed penicillin from 1987 to 2001 found

the number of second allergic responses to be less than 2 percent.

Researchers are trying to find out just how

common the allergy really is and better understand the risk of re-prescribing

penicillin, said Dr. J. Apter, a Penn

allergist and associate professor of medicine. While more work is necessary

before that happens, the study suggests that some

patients labeled as allergic can safely take the antibiotic if there's an

emergency or alternatives would be inferior, she said.

Of the 6,000 patients who had an allergic

response such as a rash or wheezing after the first prescription, about half

-- 3,014 -- received a second dose. Among those patients, only 57 -- 1.9

percent of the total -- had a similar recurrence.

If it turns out that a larger number of

people can safely take penicillin, which is highly effective and relatively

inexpensive, it would benefit public health as well as patients' wallets,

said Penn professor and senior researcher Dr. L. Strom.

Penicillin skin testing is currently

imperfect and typically unavailable to doctors because some of the testing

materials aren't widely available, Apter said.

The limitation of the study is that people

who think they're allergic to penicillin may not be, said Dr. Clifford W.

Bassett, a New

York City

allergist and a spokesman for the American Academy of Allergy, Asthma and Immunology.

" It's very important to understand that

the history of penicillin allergy is anecdotal. A lot of those probably were

not true positives, " he said. The Penn study didn't involve actual blood

or skin tests on patients, so it's hard to determine how many truly were

allergic, he said.

Some people may have had a rash or hives

that came from their illness and not the medicine. Also, every year that an

allergic person avoids penicillin may reduce their sensitivity, Bassett said.

The study appears in this month's Journal of

Allergy & Clinical Immunology.

Copyright 2004 The

Associated Press. All rights reserved.

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Deanna