A 42-year-old woman with uncomplicated acute cystitis is prescribed ciprofloxacin 500 mg twice daily for 3 days. On day 2 of therapy, she develops severe tendon pain in her right Achilles region with swelling and difficulty walking. She denies recent trauma or strenuous exercise. What is the most appropriate next step in management?

Explanation

## Clinical Presentation This patient has developed acute fluoroquinolone-induced tendinopathy, a well-recognized and potentially serious adverse effect. The temporal relationship (day 2 of ciprofloxacin) and clinical features (sudden onset, localized pain, swelling, functional impairment) are classic. ## Fluoroquinolone-Induced Tendinopathy: Key Features **Key Point:** Fluoroquinolones inhibit bacterial DNA gyrase but also interfere with human topoisomerase II, leading to collagen degradation and tendon damage. This is a class effect, though risk varies by agent. **High-Yield:** Risk factors include: - Age >60 years (though can occur at any age) - Concurrent corticosteroid use - Renal impairment - Tendinopathy history - Achilles tendon is most commonly affected (followed by patellar, rotator cuff) **Mnemonic:** FQ Tendon Risk = **AGE, STEROIDS, RENAL failure** (ASR) ## Management of Fluoroquinolone-Induced Tendinopathy | Step | Action | Rationale | |------|--------|----------| | **Immediate** | Discontinue fluoroquinolone | Continued exposure increases risk of tendon rupture | | **Immediate** | Advise rest, ice, elevation, immobilization | Reduces mechanical stress and inflammation | | **Short-term** | Switch to alternative antibiotic (e.g., nitrofurantoin, cephalosporin) | Completes UTI treatment without further tendon damage | | **Follow-up** | Consider imaging if no improvement in 2–4 weeks | Rules out rupture; guides rehabilitation | | **Avoid** | NSAIDs in acute phase (controversial; some avoid; others use cautiously) | May delay healing; ice + rest preferred | **Clinical Pearl:** Tendon rupture can occur even after discontinuation if the drug is continued. Early recognition and cessation are critical to prevent irreversible damage. ## Why Immediate Discontinuation is Correct ```mermaid flowchart TD A[Fluoroquinolone-induced tendon pain]:::outcome --> B{Continue or stop?}:::decision B -->|Continue| C[Risk of rupture increases]:::urgent B -->|Stop immediately| D[Prevent further collagen damage]:::action D --> E[Rest + immobilization]:::action E --> F[Switch to safe alternative antibiotic]:::action F --> G[Clinical improvement expected in days]:::outcome ``` [cite:Harrison 21e Ch 163; KD Tripathi 8e Ch 48]