levofloxacin
Levofloxacin (Levaquin) is an oral and intravenous fluoroquinolone antibiotic used in adults for bacterial pneumonias, skin infections, urinary tract infections, chronic bacterial prostatitis, acute bacterial sinusitis, acute bacterial exacerbation of chronic bronchitis, and post-exposure inhalational anthrax and plague. It blocks bacterial enzymes needed to copy DNA, killing the bacteria. It should be reserved when alternative treatments are not suitable.
This page is based on the European Medicines Agency assessment report for Quinsair and FDA prescribing information for levofloxacin tablets, cross-checked with MedlinePlus and the National Cancer Institute drug dictionary; the mechanism is explained in plain language, and analogies are used only where they stay accurate.
How it works
Explains what the medicine does in the body, not dosing, side effects, or safety.
An analogy
Bacteria need to unwind and copy their DNA to multiply, like unspooling a tightly wound ball of string. Levofloxacin jams the enzymes bacteria use to manage their DNA - the tools that would normally cut and re-join the strands. With those enzymes blocked, the bacteria cannot copy their genetic material and they die.
In simple terms
Levofloxacin is a fluoroquinolone antibiotic. It kills bacteria by blocking two enzymes that bacteria need to copy and repair their DNA: DNA gyrase and topoisomerase IV. Without these enzymes, bacteria cannot replicate their genetic material, and they die. Levofloxacin is used to treat a range of bacterial infections including pneumonia, skin infections, urinary tract infections, prostatitis, sinusitis, and bronchitis. It is also used for post-exposure anthrax and plague. Antibiotics like levofloxacin do not work for colds, flu, or other viral infections.
In depth
Levofloxacin is the L-isomer of the racemate ofloxacin and a member of the fluoroquinolone antibacterial class. It inhibits bacterial DNA gyrase (topoisomerase II) and topoisomerase IV with high affinity, stabilizing the DNA-enzyme cleavable complex and preventing religation of broken DNA strands. This triggers lethal double-strand DNA breaks and rapid bactericidal activity. Levofloxacin is indicated for nosocomial and community-acquired pneumonia, complicated and uncomplicated skin and skin structure infections, chronic bacterial prostatitis, complicated and uncomplicated urinary tract infections, acute pyelonephritis, acute bacterial exacerbation of chronic bronchitis, acute bacterial sinusitis, post-exposure inhalational anthrax, and plague.
See it in motion
A schematic animation of the mechanism — simplified for clarity, not drawn to scale.
Levofloxacin is a fluoroquinolone antibiotic.
- Bacteria need to unwind and copy their DNA to multiply, like unspooling a tightly wound ball of string.
- It kills bacteria by blocking two enzymes that bacteria need to copy and repair their DNA: DNA gyrase and topoisomerase IV.
- With those enzymes blocked, the bacteria cannot copy their genetic material and they die.
- Antibiotics like levofloxacin do not work for colds, flu, or other viral infections.
Target: Bacterial DNA gyrase and topoisomerase IV
Levofloxacin inhibits bacterial DNA gyrase (topoisomerase II) and topoisomerase IV, enzymes essential for DNA replication, transcription, repair, and recombination, leading to rapid bacterial cell death.
Approved uses
Approved uses differ by country and change over time. Always follow your local prescribing information.
Approved uses in European Union
EMA- Management of chronic pulmonary infections due to Pseudomonas aeruginosa in adult patients with cystic fibrosis
Approved uses in United States
FDA- Treatment of nosocomial pneumonia
- Treatment of community-acquired pneumonia
- Treatment of complicated and uncomplicated skin and skin structure infections
- Treatment of chronic bacterial prostatitis
- Post-exposure treatment of inhalational anthrax
- Treatment of plague
- Treatment of complicated and uncomplicated urinary tract infections
- Treatment of acute pyelonephritis
- Treatment of acute bacterial exacerbation of chronic bronchitis
- Treatment of acute bacterial sinusitis
Approved uses in United States
MedlinePlus- Treatment of certain bacterial infections including pneumonia, skin, and urinary tract infections
- Prevention and treatment of anthrax exposure
- Prevention and treatment of plague
Official sources
The statements on this page trace back to these records.
- Quinsair (levofloxacin) — Summary of product characteristics and package leaflet, English version
European Medicines Agency
- U.S. Food and Drug Administration: levofloxacin prescribing information
U.S. Food and Drug Administration
- MedlinePlus: levofloxacin
MedlinePlus, U.S. National Library of Medicine
- National Cancer Institute: levofloxacin
National Cancer Institute
This page explains how the medicine works — it isn’t the patient leaflet. For anything that applies to you, read the leaflet that came with your medicine or ask your pharmacist.
MedUnfold provides educational content and is not medical advice. Always follow your local prescribing information and healthcare professional.