Many people tell their doctors they are allergic to penicillin – making it the most commonly reported drug allergy.
In reality‚ although 10% of the population claims to have a penicillin allergy‚ 90% of those people are not actually allergic‚ according to the American College of Allergy‚ Asthma and Immunology. That leaves just 1% of the population who are truly allergic.
When people avoid penicillin because of a suspected allergy, they may have to take a less effective antibiotic or one with more side effects. Using broader-spectrum antibiotics when penicillin works can also contribute to antibiotic resistance.
The good news is that even if you once had an allergic reaction with a red rash and itchy hives 10 or more years ago‚ there’s a good chance your body may no longer be allergic.
Why is penicillin often the first-choice antibiotic?
Penicillin and related antibiotics such as amoxicillin and ampicillin are the gold standard for treating many bacterial infections because they are very good at killing bacteria.
Alternative broad-spectrum antibiotics such as vancomycin‚ aztreonam and ciprofloxacin aren’t as efficient at killing bacteria. They also wipe out some beneficial bacteria‚ which can put patients at risk for a host of potential problems.
Symptoms of a penicillin allergy
Penicillin allergy symptoms appear when you take penicillin or related medications like amoxicillin and ampicillin. These can include:
- Itchy‚ raised hives. Symptoms should subside after you stop taking the medication. Contact your prescriber to report the reaction and discuss an alternative treatment.
- Skin peeling or blistering. Although rare‚ these symptoms require prompt medical attention.
- Signs of anaphylaxis‚ such as shortness of breath‚ wheezing‚ throat tightness‚ vomiting‚ a racing heart or fainting. In this case, seek emergency care immediately.
Why do so many people mistakenly believe they’re allergic to penicillin?
It’s common to hear people say they’re allergic because a parent told them they developed a red rash as an infant or toddler.
A childhood rash may have been caused by the infection itself or by the infection combined with the antibiotic. Even if the antibiotic triggered the reaction‚ you may no longer be allergic.
For those who do truly have a penicillin allergy‚ more than 80% lose the allergic response after 10 years. If it’s been years‚ there’s a good chance you may no longer be allergic.
How can you confirm a penicillin allergy?
It’s best to know if you’re allergic or not before you actually need an antibiotic to fight off a bacterial infection. Consider seeing an allergist to determine whether you’re allergic.
A penicillin allergy evaluation may be especially useful for people who:
- were labeled allergic in childhood.
- cannot remember their reaction.
- experienced only a rash or have avoided penicillin for more than 10 years.
Here’s some of the information you’ll want to bring to an appointment:
- Write down the name of the medication involved‚ your age at the time‚ how soon symptoms appeared‚ how long they lasted and whether you needed medical treatment for your reaction. If you don’t remember‚ ask someone who was there‚ such as a parent or another caregiver.
- Share details of any time you have been prescribed penicillin or penicillin-related drugs since your initial reaction. Note any symptoms and outcomes you had each of those times.
An allergist may recommend a skin test first‚ followed by a supervised oral dose if the skin test is negative. People considered low risk may be able to proceed directly to an oral dose challenge in which they are given a small dose of penicillin in a supervised setting. The allergy label can be removed from your medical record if testing shows no reaction.
People with a history of a severe reaction beyond a rash should not take penicillin unless an allergist says to do so.
What risks are associated with a penicillin allergy label?
Patients with a penicillin allergy label are four times more likely to develop Clostridium difficile‚ or C. diff‚ a serious diarrheal infection. They also tend to have higher health care costs and longer hospital stays‚ likely because they cannot receive the most effective antibiotics and must instead use antibiotics that could be preserved for infections that truly require them.
What if no alternatives to penicillin are available?
If there isn’t a suitable alternative antibiotic and you’re hospitalized‚ we can use a process called desensitization to help the immune system tolerate penicillin for that course of therapy. This involves taking penicillin in increasing amounts until you can tolerate the recommended dose with minimal side effects‚ but it requires a day in the intensive care unit.
Desensitization isn’t permanent. It would have to be repeated if you need penicillin to treat future infections.
As always‚ it’s very important to let your doctor know if you have an adverse reaction to penicillin or any medication.
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