This topic will review hypersensitivity (allergic) reactions to fluoroquinolones. A general discussion of fluoroquinolones, including adverse effects other than hypersensitivity reactions, is found separately. (See "Fluoroquinolones".)
TYPES OF HYPERSENSITIVITY REACTIONS
Hypersensitivity reactions, or allergic reactions, are immunologic reactions to a drug. There are several types of hypersensitivity reactions, which are broadly divided into immediate and delayed reactions, based upon the time between administration and the appearance of signs or symptoms . Immediate reactions begin within one hour of the first administered dose, and delayed reactions begin later than one hour (and sometimes days) after the first dose. The intent of this classification system is to distinguish immediate reactions from other types, since immediate reactions are more likely to progress to potentially life-threatening anaphylaxis if the patient is re-exposed to the causative drug. Unfortunately, patients often do not recall the chronology of drug reactions and thus it is often not possible to classify reactions based on timing alone. (See "An approach to the patient with drug allergy".)
Most common — The two most common types of hypersensitivity reactions to fluoroquinolones are:
- Delayed-onset maculopapular cutaneous eruptions
- Immediate reactions, which are characterized by urticaria, pruritus, flushing, angioedema, wheezing, nausea, abdominal cramping or diarrhea, and/or hypotension
These two types of fluoroquinolone-induced hypersensitivity reactions are relatively common, and in some studies, the incidence of delayed reactions due to fluoroquinolones is comparable to that due to beta-lactams [2,3]. The remainder of this topic review will focus on these two forms of hypersensitivity.