Penicillin allergies: What parents need to know

Antibiotics in the penicillin family, such as Penicillin VK, Amoxicillin and Augmentin, are among some of the best treatments for common childhood infections like ear and sinus infections, Strep throat and bacterial pneumonia. They also have fewer side effects and cost less than other antibiotics. But, penicillin is also the most commonly reporting drug allergy. Keep reading to learn answers to frequently asked questions about penicillin allergies you may want to know for your child. 

Penicillin allergies – the real stats

Approximately 10% of people in the United States report they are allergic to penicillin antibiotics. However, a research study tested people who thought they had an allergy to penicillin. Of those tested, 9 of 10 people did not have any allergic reaction, meaning they can safely take these very helpful antibiotics. Even better news: many people with true penicillin allergies, even those with serious reactions like anaphylaxis, will outgrow their allergy over time – 50% by 5 years and 80% by 10 years after their initial allergic reaction. 

What are symptoms of a true penicillin allergic reaction? 

Some symptoms below, such as hives or diarrhea, can be simple side effects of antibiotics, but when any symptoms below begin within minutes to hours after the first dose of an antibiotic, it may be a sign of an allergic reaction (true penicillin allergy). 

• Itchy skin, flushing, hives 
• Swelling of hands & feet or skin around the eyes (angioedema) 
• Itching, tearing red eyes 
• Nasal congestion 
• Tongue and/or lip swelling 
• Throat tightness, hoarseness 
• Stomach cramps, sudden diarrhea 
• Cough, difficulty breathing/wheezing 
• Dizziness, fainting, low blood pressure 
• Anxiety, confusion 

What causes confusion about penicillin allergy? 

• Family history: Some people think they have a penicillin allergy because they have a close family member who is allergic to penicillin. However, penicillin allergies are not inherited.  
• Side effects: Symptoms such as nausea, vomiting, diarrhea and yeast infections can be mistaken for allergic reactions but are common side effects of antibiotics and are not true allergies. 
• Delayed rash: The viruses that cause colds in children can cause rashes. Sometime the virus interacts with the antibiotic in a child and can cause a rash. This usually doesn’t appear until several days after starting the antibiotic. These rashes can be mistaken for allergic reactions, even by medical professionals, but they are not caused by a “true” penicillin allergy which causes reactions within a few minutes to hours after starting the medication. 

Why does it matter if my child is labeled with a penicillin allergy?  

Patients who are thought to be allergic to penicillin are prescribed alternative antibiotics that:  

• Often do not work as well. 
• Cost more.  
• Can cause more side effects.  
• Kill more of the helpful bacteria in our bodies.   

How do I know if my child has a true allergy to penicillin or not? 

Details about your child’s previous reaction to an antibiotic may help your healthcare provider know whether your child had a “true” immediate-type allergic reaction, a delayed reaction (usually happens several days after starting penicillin) or experienced a side effect of the antibiotic (not an allergic reaction). If your child’s reaction was a side effect or a reported family history of penicillin allergy only, the allergy label can be removed from your child’s medical record without any testing.  

After gathering this information, or if you child’s prior reaction is unknown, your healthcare provider may refer your child to a specialist for further evaluation/testing to see whether your child can be treated with a penicillin antibiotic again in the future or not. This specialist will review your child’s history with you to see how best to test your child for a penicillin allergy. Patients must be older than 12 months and not on any immune suppressing medicines to have antibiotic allergy testing done.  All allergy/antihistamine medications must be stopped seven days before testing.  

What is involved with antibiotic allergy testing? 

Antibiotic allergy testing is done at Children’s Mercy Kansas City’s Infectious Disease Antibiotic Challenge Clinic (for allergy testing to penicillin and amoxicillin only) and at Children’s Mercy Allergy Clinic for these and other antibiotics. Antibiotic challenge testing at Children’s Mercy is done safely in an office setting with qualified healthcare providers present.  

Typically, prior reaction information is gathered by telephone before scheduling the clinic visit. If your child had hives or a rash while on a penicillin before, your child would be given an oral dose of the antibiotic and observed for 1-2 hours for any reaction. If your child previously had a serious reaction to a penicillin or if the specialist has concerns related to the type of reaction, your child may have a skin test followed by the oral antibiotic. If your child does not react during the visit, they are unlikely to have a serious immediate reaction when they receive this antibiotic in the future. At the end of the visit, you will leave with clear written information about what antibiotics your child can or cannot take in the future.  

Is penicillin allergy testing covered by insurance? 

Many insurance plans do cover penicillin allergy testing. However, we recommend checking with your insurance plan(s) for questions about coverage.  

Is my child allergic to penicillin? 

It’s important to know. Ask your child’s primary care provider about a referral for penicillin allergy evaluation at Children’s Mercy.  

Contributing Authors: 

• Jennifer McKinsey, MD, Physician, Division of Urgent Care 
• Amanda Nedved, MD, Director of Quality Improvement for Urgent Care 
• Rana El Feghaly, MD, MSCI, Director Outpatient Antimicrobial Stewardship Program 
• Sheryl Chadwick, Program Manager, Patient and Family Engagement 
• Tiffany Addington, MD, FAAP, Medical Director, Children’s Mercy East Urgent Care 
• Annie Wirtz, PharmD, PCPPS – Clinical Pharmacy Specialist, Infectious Diseases