Nearly all quinolone antibiotics in use are fluoroquinolones, which contain a fluorine atom in their chemical structure and are effective against both Gram-negative and Gram-positive bacteria.

​Fluoroquinolones “kill bacteria by blocking enzymes which normally untangle DNA during cell replication. Usually, these enzymes cut DNA’s double helix, pass another part of the strand through the gap, and then mend the cut. 

​But quinolones bind to the enzymes, preventing them from mending their cuts. In the 1980s, researchers added fluorine atoms to the quinolones’ structures. This allowed the antibiotics to penetrate tissues throughout the body, including the central nervous system, and boosted their effectiveness against a broad range of bacterial infections.” (2)

​Fluoroquinolones are of value in certain infections, including some life-threatening ones, where alternative antibiotics are not sufficiently effective.

​But fluoroquinolones, as with many antibiotics, have been overused. Serious side effects have been associated with them over the years, and numerous cautions from the FDA limit their use. A number of label changes have been mandated, and some fluoroquinolones even have black box warnings. (3)