AMOXICILLIN ALLERGY: WHEN IS THE RASH REALLY AN ALLERGY? Anu Ravi, M.D. Division of Pediatric Allergy Mayo Clinic Pediatric Days January 16, 2024 Amoxicillin is a penicillin antibiotic that fights bacteria. It is used to treat many types of infections such as tonsillitis, bronchitis, pneumonia, and others. Have you been prescribed amoxicillin or another penicillin since your reaction? Did you experience any side effects? Based on a patient's history, penicillin allergy risk categories can be determined. Learn about rashes from amoxicillin, identifying side effects, what amoxicillin is used for, what it treats and ensure accurate diagnosis and rash treatment. Here’s what an amoxicillin rash looks like, how to treat it, and when to see a doctor. If a suspected mild allergic reaction occurs, such as localized hives or itching without difficulty breathing or swelling, immediately stop taking amoxicillin. Contact the prescribing physician or a medical professional for guidance on alternative medications and symptom management. About 10% of people develop a rash after taking the antibiotic amoxicillin. However, only around 1% are true allergies. Learns why this matters and what you can do. It is generally recommended that you avoid all drugs in the immediate penicillin family (amoxicillin, ampicillin, amoxicillin-clavulanate, dicloxacillin, nafcillin, piperacillin-tazobactam as well as certain drugs in the cephalosporin class (a closely related class to penicillins). Find out how to identify delayed allergic reactions to amoxicillin and when to contact a healthcare provider. It's important to understand and discuss what is an allergic reaction, what is a typical side effect and what you can tolerate in taking a medicine. Call 911 or emergency medical help if you experience symptoms of a serious reaction or possible anaphylaxis after taking penicillin.