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Penicillin allergies are rarer than you think

The theme for this year’s Antibiotic Awareness Week is to ‘Think Twice. Seek Advice,’ a message to help patients and doctors start a conversation about reported penicillin allergies.
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About 10 per cent of Canadians have a penicillin allergy in their medical record but much less than one per cent have a true allergy. As part of Antibiotic Awareness Week, which runs November 18 to 24, the Antibiotic Wise team at the BC Centre for Disease Control (BCCDC) is drawing attention to potentially inaccurate penicillin allergy records to help fight antibiotic resistance in B.C.

“Patients with a reported allergy to penicillin often end up with prescriptions that are more likely to cause side effects and unintended harm,” said Dr. David Patrick, interim executive lead for the BCCDC and medical lead of the antimicrobial resistance program. “Alternative antibiotics used in place of penicillins may be more likely to kill good bacteria and their overuse can increase the risk of antibiotic resistant infections, putting everyone at risk.”  
When bacteria develop resistance to antibiotics, these same antibiotics may not work in the future. Bacteria that have developed antibiotic resistance are known as superbugs and are very difficult to treat. About 26 per cent of infections in Canada are resistant to first-line antibiotics (those prescribed first to treat an infection) and it’s estimated that could grow to 40 per cent by 2050. This would have an economic impact of $13 to 21 billion per year, according to a report released last week from a panel of Canadian experts including Dr. Patrick.

Penicillins were the first group of antibiotics discovered in the early 20th century and are among the most prescribed antibiotics in B.C. Penicillins are used to treat common bacterial infections like skin, ear, sinus, dental and some respiratory infections.

Patients and physicians often believe individuals are having an allergic reaction to penicillin when in most cases their symptoms are temporary, mild or a symptom of something else. For example, having a mild upset stomach is the most common side effect for antibiotics. On average, only five out of every 10,000 people in B.C. have a true, serious allergy to penicillin, and approximately one in 100 have other adverse reactions. In 80 per cent of cases, adverse effects related to penicillins disappear over time. 

“It’s important to talk to your doctor about whether a penicillin allergy is listed in your medical records as this could impact your health,” said Dr. Patrick. “People prescribed other antibiotics often experience more side effects and the drugs are often less effective compared to penicillins.”

The Antibiotic Wise team has launched a penicillin allergy campaign, encouraging doctors and patients to have a conversation about their reported penicillin allergy to assess whether they may be able to try penicillin antibiotics safely.

Antibiotics and pregnancy
BC Women’s Hospital + Health Centre launched a penicillin allergy clinic in summer 2019 to safely test and monitor patients to determine whether they have a true penicillin allergy. The clinic is the first of its kind in North America and sees patients who are registered to deliver their baby at BC Women’s and are referred by their care provider. 

Penicillin allergy is reported in approximately 10 per cent of pregnant women, but when evaluated appropriately, 90 per cent of these patients can safely receive penicillin because they do not have a true allergy or they have outgrown the allergy. 

“Penicillin is a beta lactam antibiotic and is amongst one of the safest antibiotics to use in pregnancy as it narrowly targets only certain bacteria without potentially eliminating other bacteria that help our bodies digest food and absorb nutrients,” said Dr. Chelsea Elwood, reproductive infectious diseases specialist at BC Women’s Hospital + Health Centre.
The use of alternative antibiotics has been linked to increased infections of caesarean section incisions and may lead to long-term chronic illnesses for babies exposed in early infancy. The removal of an unverified penicillin allergy can improve health outcomes by lowering the incidence of adverse effects related to the use of broad spectrum antibiotics which are used to treat a wide range of bacteria. 

Key facts about penicillin allergy and antibiotic resistance
  • Less than five in 10,000 people have a true serious allergy to penicillin.
  • One in 100 experience adverse effects.
  • 80 per cent of adverse effects related to penicillin disappear within 10 years.
  • If you’re mistakenly listed as having a penicillin allergy in your medical records, you may be prescribed a more powerful antibiotic with greater side effects. 
  • Research shows that individuals labelled as penicillin-allergic suffer more adverse effects and are at greater risk for C. difficile infection.
Learn more:

Health care practitioners can request campaign materials (posters and brochures) by emailing




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