Causality assessment · Causality: well established

Levofloxacin (fluoroquinolones) and Aortic aneurysm / dissection: is the FAERS signal real?

n=113 co-reports · PRR 5.2 · ROR 5.2

Levofloxacin (fluoroquinolones) side-effect profile All assessments See in the full list

A written Bradford Hill assessment of one drug–event pair. The grade is a judgement about the signal, not a statement that this drug causes this event in any one person; FAERS counts are reports, not rates.

Causality: well established

Levofloxacin (fluoroquinolones) ↔ Aortic aneurysm / dissection

n=113 co-reports · PRR 5.2 · ROR 5.2

Fluoroquinolones such as levofloxacin are associated with an increased risk of aortic aneurysm and dissection, thought to reflect their effects on collagen and matrix metalloproteinases in the vessel wall. This is a genuinely new safety concern: after observational studies and label reviews, the FDA added a class warning in 2018 and advises avoiding fluoroquinolones in patients at high risk (those with prior aneurysm, hypertension, or connective-tissue disease). The 113 co-reports (PRR 5.2) are relatively small because aortic events are uncommon, but the regulatory basis is now explicit.

Regulatory basis: FDA 2018 class warning on fluoroquinolones and aortic aneurysm/dissection; levofloxacin prescribing information.

Bradford Hill viewpoint	Status	Note
Temporality (necessary)	met	Aortic events occur in patients exposed to the drug, with observational studies linking current use to risk
Strength	partial	PRR 5 on a small co-report count — a modest statistical signal for a serious outcome
Consistency	met	Supported by multiple large observational cohort studies and a class label change
Specificity	met	A fluoroquinolone-class effect rather than levofloxacin-specific
Biological gradient	partial	Risk rises with age, hypertension, and connective-tissue disease
Plausibility	met	Collagen degradation and matrix-metalloproteinase effects in the vessel wall are proposed
Coherence	met	Coheres with the current class warning to avoid the drugs in high-risk patients
Experiment	partial	Observational; no randomized trial has tested aortic outcomes
Analogy	met	Analogous to the aortic risk across the fluoroquinolone class

This page's own qualitative read, not an automated/citation-gated assessment.

✗ No ClinicalTrials.gov results-posting trial in the top search hits for levofloxacin captured aortic aneurysm or dissection; the risk was identified through large observational studies and a 2018 FDA class warning, not trial AE tables.