People who have had an allergic reaction to penicillin might believe they need to avoid it for life. But for most people, that's not true. In fact, 80 percent of people who have an allergic reaction to penicillin lose their allergy within 10 years, if not exposed to penicillin again in that time period.
"Unfortunately, most people who lose their penicillin allergy do not realize it," said Kristen Eblen, antimicrobial stewardship lead pharmacist at Lake Regional Health System. "As a result, their doctors must prescribe more powerful antibiotics to treat simple infections. This increases their chances of having severe side effects and developing difficult-to-treat infections. For example, patients who report a penicillin allergy are more likely to develop C. difficile, a serious infection causing severe diarrhea and even death. They also are more likely to develop MRSA, a difficult-to-treat infection usually requiring IV antibiotics."
To help people avoid these negative effects, Lake Regional Outpatient Services now provides penicillin skin testing, a safe way to determine if a penicillin allergy is still active.
How Does Skin Testing Work?
Testing usually takes about two hours to complete. The skin is pricked and injected with weak solutions of penicillin and observed for a reaction. This may cause discomfort due to itching, but it is not painful.
A positive skin reaction is an itchy, red bump that lasts about half an hour and then resolves. A positive test indicates that the person is truly allergic. People with a positive test should continue to avoid penicillin.
If the patient completes the skin testing without a positive reaction, a single oral dose of full-strength penicillin is commonly given to confirm that the patient does not have an allergy to the medication. About three percent or less of people with a history of penicillin allergy and a negative skin test will still experience an allergic reaction. However, these reactions are very mild.
If a person has a negative skin test and has no reaction to an oral dose of the antibiotic, no future precautions are necessary.
What Does a Negative Test Result Mean?
Approximately 90 percent of people will test negative — meaning they do not have a penicillin allergy — either because they lost the allergy or because they were never truly allergic in the first place. These people can safely take penicillin and related antibiotics. Their chance of an allergic reaction is as low as most people's.
When is Testing Not Recommended?
Penicillin skin testing does not provide any information about certain types of reactions. These include extensive blistering and peeling of the skin (Stevens-Johnson syndrome or toxic epidermal necrolysis), a widespread sunburn-like reaction that later peeled (erythroderma) or a rash composed of small bulls-eyes or target-like spots (erythema multiforme). People with these types of reactions should never again be given the medication that caused the reaction. This applies to all situations because a second exposure could cause a severe progressive reaction and even death.
What is the First Step?
The first step to getting this important test is to discuss it with a doctor.
"Your doctor will ask about your penicillin allergy — when it occurred and what symptoms you had," Eblen said. "If they determine you are a good candidate for this testing, they will issue an order. Getting tested is especially important if you are having an upcoming surgery, are prone to COPD exacerbations or pneumonia, or are frequently prescribed antibiotics."
Lake Regional Health System provides comprehensive health care services to the residents and visitors of the lake area. The hospital is accredited by The Joint Commission and is a three-time recipient of the Missouri Quality Award. Lake Regional also operates primary care, walk-in care, specialty care and rehab therapy clinics; retail pharmacies; and home health and hospice services throughout the lake area.