Penicillin allergy is an abnormal reaction of your immune system to the antibiotic drug penicillin. Penicillin is prescribed for treating various bacterial infections. Show
Common signs and symptoms of penicillin allergy include hives, rash and itching. Severe reactions include anaphylaxis, a life-threatening condition that affects multiple body systems. Research has shown that penicillin allergies may be over-reported — a problem that can result in the use of less-appropriate and more-expensive antibiotic treatments. Therefore, an accurate diagnosis is needed when penicillin allergy is suspected to ensure the best treatment options in the future. Other antibiotics, particularly those with chemical properties similar to penicillin, also can result in allergic reactions. Products & Services
Symptoms Close Drug rashDrug rashA drug rash usually starts within two weeks of taking a new medication and begins as discrete red spots that spread, covering large areas of the body. Signs and symptoms of penicillin allergy often occur within an hour after taking the drug. Less commonly, reactions can occur hours, days or weeks later. Penicillin allergy signs and symptoms may include:
AnaphylaxisAnaphylaxis is a rare, life-threatening allergic reaction that causes the widespread dysfunction of body systems. Signs and symptoms of anaphylaxis include:
Delayed reactions resulting from penicillin allergyLess-common penicillin allergy reactions occur days or weeks after exposure to the drug and may persist for some time after you stop taking it. These conditions include:
Adverse events that are not allergic reactionsYou may experience side effects of penicillin — as happens with other medications — that are not an allergic reaction to the drug. Depending on the type of penicillin, common side effects may include mild nausea or diarrhea, headache, or vaginal itching. Signs or symptoms of an infection for which you are being treated — or unrelated symptoms — also may be mistaken as an allergic drug reaction. When to see a doctorSee your doctor as soon as possible if you experience signs or symptoms of penicillin allergy. 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 medication. Call 911 or emergency medical help if you experience signs of a severe reaction or suspected anaphylaxis after taking penicillin. Request an Appointment at Mayo Clinic There is a problem with information submitted for this request. Review/update the information highlighted below and resubmit the form. Sign up for free, and stay up to date on research advancements, health tips and current health topics, like COVID-19, plus expertise on managing health. Email ErrorEmail field is required ErrorInclude a valid email address To provide you with the most relevant and helpful information, and understand which information is beneficial, we may combine your email and website usage information with other information we have about you. If you are a Mayo Clinic patient, this could include protected health information. If we combine this information with your protected health information, we will treat all of that information as protected health information and will only use or disclose that information as set forth in our notice of privacy practices. You may opt-out of email communications at any time by clicking on the unsubscribe link in the e-mail. |
