Title : Ciprofloxacin ear drops associated acute bursitis: A case report
Abstract:
Background: Fluoroquinolone antibiotics are associated with serious musculoskeletal adverse effects, most commonly Achilles tendinopathy. Following the 2019 MHRA and European Medicines Agency safety review, and strengthened restrictions issued in January 2024, systemic fluoroquinolones are now reserved for cases where no alternative antibiotic is appropriate. The potential for topical otic fluoroquinolone preparations to precipitate musculoskeletal toxicity remains underappreciated in clinical practice.
Case Presentation: An 18-year-old woman presented to the emergency department with a one-day history of acute left knee swelling, warmth, and pain on weight-bearing without antecedent trauma. Examination revealed periarticular swelling with localised erythema and a preserved range of motion to ninety degrees. Plain radiography demonstrated a small joint effusion with no fracture or erosions. The working diagnosis was acute bursitis. A comprehensive drug history, explicitly including topical preparations, revealed recent use of ciprofloxacin ear drops for otitis externa, which the patient had self-discontinued on noticing knee symptoms. She was treated with flucloxacillin and a non-steroidal anti-inflammatory agent. On follow-up, symptoms had improved significantly following cessation of ciprofloxacin — a dechallenge response supporting a probable adverse drug reaction on the Naranjo scale. A Yellow Card report was submitted to the MHRA and written patient consent for publication was obtained.
Discussion: Fluoroquinolone musculoskeletal toxicity is a class effect involving inhibition of tenocyte proliferation and upregulation of matrix metalloproteinases — processes relevant to both tendinous and bursal tissue. Whilst systemic absorption from otic preparations is generally considered minimal with an intact tympanic membrane, the inflamed and disrupted epithelium of the external auditory canal in acute otitis externa may permit greater systemic absorption than is typically assumed. The temporal association and dechallenge response in this case support a probable causal relationship.
Conclusion: This case highlights two important clinical messages. First, fluoroquinolone musculoskeletal toxicity should remain on the differential even when the prescribing route is topical. Second, the drug history in any acute soft tissue presentation must explicitly include ear drops, eye drops, and other topical preparations — agents that patients rarely volunteer and clinicians rarely ask about. Suspected adverse drug reactions involving topical fluoroquinolones should be reported via the MHRA Yellow Card scheme to strengthen national pharmacovigilance data.
