Fluoroquinolone Antibiotic Pregnancy: Contraindicated in pregnancy and breast-feeding (UK SPC 4.3/4.6). US labelling: Pregnancy Category C.

Levofloxacin

Brand names: Tavanic

Levofloxacin is a fluoroquinolone antibacterial, the active L-isomer of ofloxacin, used for respiratory, urinary, skin and certain other infections when alternatives are unsuitable.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 500 mg

Route: oral

Frequency: once daily (up to twice daily for severe infections)

Infection / infectious diseases context - UK SPC (normal renal function) by indication: community-acquired pneumonia 500 mg once or twice daily 7-14 days; complicated skin and soft-tissue infection 500 mg once or twice daily 7-14 days; complicated UTI 500 mg once daily 7-14 days; chronic bacterial prostatitis 500 mg once daily 28 days; inhalation anthrax 500 mg once daily for 8 weeks (US labelling: inhalational anthrax post-exposure 500 mg once daily for 60 days; plague 500 mg once daily for 10-14 days - verify vs UK SPC). Not recommended for known or suspected MRSA unless susceptibility is confirmed (co-resistance to fluoroquinolones is likely). Reserve for infections where other antibacterials are inappropriate. Swallow whole; take at least 2 hours before or after iron/zinc salts, magnesium- or aluminium-containing antacids, didanosine or sucralfate. Oral and IV forms are bioequivalent (same dose). Contraindicated in children and growing adolescents (<18 years).

Dose adjustments

Renal

Required when CrCl <=50 ml/min. Example for a 500 mg/24 h regimen: first dose 500 mg, then CrCl 50-20 ml/min 250 mg/24 h; CrCl 19-10 ml/min 125 mg/24 h; CrCl <10 ml/min (incl. haemodialysis/CAPD) 125 mg/24 h. For a 500 mg/12 h regimen: first dose 500 mg, then CrCl 50-20 give 250 mg/12 h, CrCl 19-10 give 125 mg/12 h, CrCl <10 give 125 mg/24 h. No additional dose is needed after haemodialysis or CAPD.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to levofloxacin, other quinolones, or any of the excipients
Epilepsy
History of tendon disorders related to fluoroquinolone administration
Children or growing adolescents (<18 years)
Pregnancy
Breast-feeding

Side effects

Nausea
Headache
Diarrhoea
Insomnia
Dizziness
Constipation

Interactions

Iron/zinc salts, magnesium- or aluminium-containing antacids, didanosine, sucralfate - reduce levofloxacin absorption; separate doses by at least 2 hours (eMC 4.2; US label 7)
Warfarin - anticoagulant effect may be enhanced; monitor INR/prothrombin time and for bleeding (US label 7)
Antidiabetic agents - dysglycaemia reported; monitor blood glucose (US label 7)

Clinical monograph

How it works

It inhibits the bacterial enzymes DNA gyrase and topoisomerase IV, blocking DNA replication, transcription and repair, leading to bacterial cell death.

Prescribing in practice

MHRA advice restricts fluoroquinolones because of rare but disabling, potentially long-lasting or irreversible musculoskeletal and neurological effects, including tendon rupture, so they should be reserved for situations where other antibacterials cannot be used.
It prolongs the QT interval and lowers the seizure threshold, warranting caution with other QT-prolonging drugs and in those at risk of convulsions.
Absorption is reduced by antacids and iron, zinc or calcium products, which must be separated from the dose.

Monitoring

Review for tendon pain, neuropathy, neuropsychiatric symptoms and, where relevant, QT interval, stopping treatment at the first sign of serious adverse effects.

Counselling the patient

Stop the antibiotic and seek advice if you develop tendon pain or swelling, numbness, or new mood or sleep changes.
Separate indigestion remedies and iron, zinc or calcium supplements from your dose.
Avoid excessive sun exposure and report any new joint or muscle problems.

Evidence & guidelines

Use is governed by MHRA and NICE guidance restricting fluoroquinolones to situations where other antibacterials are inappropriate.

Reference: MHRA Drug Safety Update 2019; NICE Antimicrobial Prescribing Guidance; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

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