Drug Allergy

Penicillin, Other Antibiotic and Drug Allergies

Drug allergy occurs when the immune system reacts abnormally to a medication, causing symptoms such as rashes, swelling, breathing difficulty, or in rare cases, anaphylaxis. Antibiotics – especially penicillins, cephalosporins, sulpha drugs, are the most common culprits, but reactions can also occur to other medications such as anti-inflammatory drugs, anaesthetics, or chemotherapy agents.

Penicillin allergy is one of the most frequently reported drug allergies, affecting up to one in five Australians. However, research shows that around 95% of people labelled as penicillin-allergic are not truly allergic when formally tested. Many reactions reported in childhood such as mild rashes or side effects are not true allergies and often resolve over time. Being incorrectly labelled as penicillin-allergic can lead to the use of less effective antibiotics which can also contribute to antibiotic resistance and poorer outcomes. For this reason, penicillin de-labelling programs have become an important part of modern allergy practice.

Assessment involves a careful history, possible skin testing, and often a supervised oral challenge to confirm tolerability. Australian data show that over 95% of low-risk patients can be safely de-labelled, enabling access to optimal first-line antibiotics.

Similar principles apply to investigating allergies to other antibiotics and medications -specialist evaluation helps clarify whether a true allergy exists and guides safe future drug use.

If you have ever been labelled with a medication allergy, consider speaking to your GP to obtain a referral for specialist allergy assessment.

Getting the right diagnosis and removing incorrect allergy labels can help you receive better care and reduce unnecessary antibiotic use in the community.

Food Challenges

Questions? We got you.

How do I book an appointment?

The first step in booking an appointment is to obtain a referral from your GP or another specialist. While a referral is not required, having one enables you to claim applicable Medicare rebates and helps our team appropriately triage your condition for review. Once you have your referral, you can schedule an appointment by booking online or contacting our practice directly and uploading your referral – our team will be in touch to schedule an appointment

Please bring a valid referral letter, Medicare card, and any recent investigation results, previous skin prick or patch testing reports, and relevant medical correspondence. For children, bringing their red book with recent growth measurements is also helpful.

Avoid antihistamines for 3–5 days before your appointment, as they can affect skin testing. You may continue nose sprays, asthma medications, antibiotics, and steroid creams. Do not apply moisturisers or topical steroids on areas likely to be tested (for example forearms, legs, back).

If you are suffering from a condition that you need to take oral anti histamines or steroids to control to manage your symptoms, continue to take those medications. Our doctors can arrange other forms of testing if required after the consultation.

Initial appointments approximately take around an hour, which may include skin prick testing if required. Follow-up appointments are typically shorter.

We prefer face-to-face appointments but we also offer telehealth consultations for selected patients or circumstances.

Harmony Allergy & Immunology Clinic is conveniently accessible by public transport, including Translink bus services. The Sunnybank clinic offers free onsite parking and street parking is also available around the Sunnybank hospital.

Skin prick testing applies a small amount of allergen (commercial extract or fresh food) to the skin which is then gently pricked to check for a reaction. The test takes 1–2 minutes, with results read after 15–20 minutes. Your doctor will determine if it’s appropriate for you.

Allergy testing is done by trained staff in a fully equipped medical setting. Reactions are rare, usually limited to mild itchiness at the test site, and can be promptly treated if needed.

Ensure you are well and avoid antihistamines 3–5 days before the test. Bring entertainment (toys, books, iPad, laptops) and for children, their favourite foods. You may need to bring the food or drug being tested which the staff will advise. We do not recommend bringing siblings; if necessary, bring an extra support person.

Ensure you are well before your appointment. You will be monitored by a health practitioner for at least 30 minutes after your immunotherapy dose. If taking your medication or vaccine home, please bring a small cooler with ice pack.

Are you ready to request an appointment?

Schedule a consultation with our experts to discuss your allergy needs.