Fluoroquinolone antibiotic Pregnancy: Contraindicated in pregnancy and breastfeeding. The safety of moxifloxacin in human pregnancy has not been evaluated; animal studies have shown reproductive toxicity and the potential risk for humans is unknown. Due to the experimental risk of fluoroquinolone damage to weight-bearing cartilage of immature animals and reversible joint injuries described in children, moxifloxacin must not be used in pregnant women. Breast-feeding is contraindicated during moxifloxacin therapy.

Moxifloxacin

Brand names: Avelox, Moxivig (eye)

Moxifloxacin is a fluoroquinolone antibacterial used for respiratory and certain other infections, available orally, intravenously and as eye drops.

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: 400 mg

Route: Oral (film-coated tablet, swallowed whole with sufficient liquid; may be taken independent of meals)

Frequency: Once daily

Max: 400 mg per day — the recommended dose (400 mg per day) and duration of therapy for the indication being treated should not be exceeded

SPC §4.2: 'The recommended dose is one 400 mg film-coated tablet once daily.' Treatment durations by indication: acute exacerbation of chronic obstructive pulmonary disease including bronchitis 5-10 days; community acquired pneumonia 10 days; acute bacterial sinusitis 7 days; mild to moderate pelvic inflammatory disease 14 days. Moxifloxacin has been studied in clinical trials for up to 14 days of treatment. Sequential (intravenous followed by oral) therapy: in clinical studies most patients switched from intravenous to oral therapy within 4 days (community-acquired pneumonia) or 6 days (complicated skin and skin structure infections); recommended total duration of intravenous plus oral treatment is 7-14 days for community-acquired pneumonia and 7-21 days for complicated skin and skin structure infections. Special populations: no adjustment of dosage is required in the elderly or in patients with low bodyweight. Paediatric population: moxifloxacin is contraindicated in children and adolescents (under 18 years); efficacy and safety in children and adolescents have not been established.

Dose adjustments

Renal

No adjustment of dosage is required in patients with mild to severely impaired renal function or in patients on chronic dialysis (haemodialysis and continuous ambulatory peritoneal dialysis). There is insufficient data in patients with impaired liver function.

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 moxifloxacin, other quinolones or to any of the excipients
Pregnancy and lactation
Patients below 18 years of age
History of tendon disease/disorder related to quinolone treatment
Congenital or documented acquired QT prolongation
Electrolyte disturbances, particularly uncorrected hypokalaemia
Clinically relevant bradycardia
Clinically relevant heart failure with reduced left-ventricular ejection fraction
Previous history of symptomatic arrhythmias
Impaired liver function (Child Pugh C) and patients with transaminases increased more than 5-fold ULN

Side effects

Nausea and diarrhoea (the most frequent reactions; apart from these, all adverse reactions were observed at frequencies below 3%)
Headache and dizziness (common, nervous system disorders)
Superinfections due to resistant bacteria or fungi, e.g. oral and vaginal candidiasis
QT interval prolongation (in patients with hypokalaemia, and uncommonly in others) — see SPC §4.3 and §4.4
Prolonged, disabling and potentially irreversible serious adverse reactions affecting musculoskeletal, nervous, psychiatric and sensory systems, reported with quinolones and fluoroquinolones irrespective of age or pre-existing risk factors
Tendon disorders, peripheral neuropathy and polyneuropathy, seizures including grand mal convulsions, and hypersensitivity/anaphylaxis including very rarely life-threatening shock and angiooedema

Interactions

Other medicinal products that prolong the QT interval — moxifloxacin should not be used concurrently (SPC §4.3/§4.5)
Medication that can reduce potassium levels — use with caution in patients receiving moxifloxacin (SPC §4.4)
Multivalent cation-containing products (antacids containing aluminium or magnesium, sucralfate, iron, multivitamins containing iron or zinc, didanosine buffered formulations) — substantially reduce absorption; take moxifloxacin at least 4 hours before or 8 hours after these agents (US label §7.1)
Warfarin — anticoagulant effect enhanced; monitor prothrombin time/INR and bleeding (US label §7.2)
Class IA and Class III antiarrhythmics — proarrhythmic effect may be enhanced; avoid concomitant use (US label §7.5)
Antidiabetic agents — carefully monitor blood glucose (US label §7.3)

Clinical monograph

How it works

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

Prescribing in practice

The MHRA advises that systemic fluoroquinolones may cause disabling and potentially long-lasting tendon, muscle, joint and nervous-system effects, and aortic aneurysm/dissection, so they should be reserved for when other antibiotics are unsuitable.
Moxifloxacin prolongs the QT interval and should be avoided with other QT-prolonging drugs and in patients with relevant cardiac risk factors.
It should be used with caution in epilepsy and conditions predisposing to seizures, and tendon rupture risk is increased with corticosteroids and in older patients.

Monitoring

Monitor for tendon, neurological and cardiac symptoms, and consider ECG assessment where QT-prolongation risk factors are present.

Counselling the patient

Stop the medicine and seek advice if you develop tendon pain or swelling, new pins-and-needles, or mood changes.
Avoid taking it at the same time as indigestion remedies or iron and calcium supplements, which reduce absorption.

Evidence & guidelines

Restrictions on fluoroquinolone use follow MHRA Drug Safety Updates, and efficacy in respiratory infection is established in clinical trials and the SPC.

Reference: MHRA Drug Safety Update; UK AMR; 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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