Penicillin allergy

Penicillin allergy is an immune-mediated reaction to penicillin drugs. Symptoms range from mild skin reactions to life-threatening anaphylaxis.

Immediate hypersensitivity: An immune reaction that begins within minutes to hours, often through IgE antibodies and mast-cell activation. This pathway underlies rapid reactions such as hives, swelling, and anaphylaxis.
Penicillin allergy testing: A clinical evaluation using history and, when appropriate, skin tests and supervised drug challenge. Testing can assess whether a reported penicillin allergy is still present.
Antibiotic resistance: The ability of microorganisms to survive or grow despite exposure to drugs intended to kill or inhibit them. Substituting broader-spectrum antibiotics after an unverified allergy label can contribute to resistance pressures.
Adverse drug reaction: An unwanted or harmful response associated with the use of a medication. This broader category includes allergy as well as nonimmune side effects.
Delayed hypersensitivity: An immune reaction that develops hours to days after exposure, commonly involving T cells. Many penicillin-associated rashes emerge after treatment has begun rather than immediately.
Drug provocation test: A supervised administration of a medication in increasing or therapeutic doses to assess tolerance. A negative challenge can confirm tolerance when risk assessment supports testing.
Clostridioides difficile infection: An intestinal infection that can cause diarrhea and colitis, often after antibiotic-associated disruption of gut microbes. Alternative antibiotics used because of allergy labels may carry different risks, including this infection.
Drug intolerance: A nonimmune adverse response to a medication that occurs at an ordinary dose. Nausea or other predictable side effects may be mislabeled as penicillin allergy.
Hapten: A small molecule that can trigger an immune response after binding to a larger carrier molecule. Penicillin breakdown products can bind proteins and create targets the immune system recognizes.
Penicillin skin testing: A diagnostic procedure that applies selected penicillin reagents to the skin to assess immediate sensitization. It can help evaluate suspected IgE-mediated penicillin allergy.

Linked from 9 pages