A 72-year-old woman who started ciprofloxacin 500 mg BID five days ago for a complicated UTI calls the clinic reporting sudden-onset pain and swelling behind her right ankle that began while walking to the mailbox. She has a history of kidney transplant and takes prednisone 5 mg daily. On exam, the Achilles tendon region is warm, tender, and mildly swollen with pain on active plantar flexion. Which of the following is the most appropriate next step?

Question

Accepted Answer

✅ C. Discontinue ciprofloxacin immediately, immobilize the ankle with a splint or walking boot, and urgently refer to orthopedics
Fluoroquinolones (ciprofloxacin, levofloxacin, moxifloxacin) carry an FDA BLACK BOX WARNING for tendinitis and tendon rupture — most commonly the Achilles tendon. Risk is markedly increased in adults older than 60, patients on systemic corticosteroids, and solid-organ or bone-marrow transplant recipients. This patient has all three risk factors. Any new tendon pain on a fluoroquinolone must be treated as a presumed partial tear until proven otherwise: stop the drug, immobilize, avoid weight-bearing, and obtain orthopedic evaluation. Tendon injury can occur within hours of the first dose or weeks after discontinuation.

❌ A. Continue ciprofloxacin and recommend ibuprofen for symptomatic relief
Continuing the fluoroquinolone risks progression from tendinitis to complete rupture. NSAIDs may also potentiate fluoroquinolone CNS toxicity and do not address the underlying drug-induced tendinopathy.

❌ B. Reassure and recommend stretching exercises with weight-bearing as tolerated
Stretching and continued weight-bearing on a fluoroquinolone-affected Achilles tendon can convert partial injury to complete rupture. This is the opposite of what is needed.

❌ D. Switch to levofloxacin 750 mg daily since it has a different side-effect profile
All fluoroquinolones share the class-wide tendon black-box warning — levofloxacin is not safer in this regard. The patient needs a non-fluoroquinolone alternative such as a carbapenem or culture-directed therapy.

:::danger
Fluoroquinolone tendon black box: STOP the drug at first sign of tendon pain. Highest risk: age over 60, corticosteroids, transplant recipients. Achilles is the classic site; rupture can occur even after the drug is stopped.
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Ciprofloxacin

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⚙️ Mechanism of Action

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