Fluoroquinolones associated with development of serious, sometimes fatal, hypoglycemia. Hyperglycemia also associated with use of fluoroquinolones. Severe hypersensitivity reactions, including anaphylaxis, have occurred with quinolone therapy. Use of quinolones has been linked to peripheral neuropathy (rare). Avoid excessive sunlight (may cause moderate-to-severe phototoxicity reactions). Prolonged use may result in fungal or bacterial superinfection, including C. difficile-associated diarrhea and pseudomembranous colitis. Tendon inflammation and/or rupture reported (risk may be increased with concurrent corticosteroids, organ transplant recipients, and in patients >60 years of age). Use with caution in significant bradycardia or acute myocardial ischemia. Some quinolones may exacerbate myasthenia gravis (rare, potentially life-threatening weakness of respiratory muscles may occur). Use with caution in renal impairment, and in rheumatoid arthritis (might increase risk of tendon rupture). Use with caution in individuals at risk of seizures (CNS disorders or concurrent therapy with medications which may lower seizure threshold). Potential for seizures, although very rare, may be increased with concomitant NSAID therapy. Adverse effects (e.g. tendon rupture, QT changes) may be increased in the elderly. Hemolytic reactions may (rarely) occur with quinolone use in latent or actual G6PD deficiency.