Fluoroquinolones associated with development of serious, and sometimes fatal, hypoglycemia. Hyperglycemia also associated with use of fluoroquinolones. Fluoroquinolones may prolong QTc interval (avoid use in history of QTc prolongation, uncorrected hypokalemia, hypomagnesemia, or concurrent administration of other medications known to prolong the QT interval (including Class Ia and Class III antiarrhythmics, cisapride, erythromycin, antipsychotics, and tricyclic antidepressants)). Adverse effects (e.g. tendon rupture, QT changes) may be increased in the elderly. Severe hypersensitivity reactions, including anaphylaxis, occurred with quinolone therapy (reactions may present as typical allergic symptoms (e.g. itching, urticaria, rash, edema) after a single dose, or may manifest as severe idiosyncratic dermatologic (e.g. Stevens-Johnson, toxic epidermal necrolysis), vascular (e.g. vasculitis), pulmonary (e.g. pneumonitis), renal (e.g. nephritis), hepatic (e.g. hepatic failure or necrosis), and/or hematologic (e.g. anemia, cytopenias) events, usually after multiple doses). Tremor, restlessness, confusion, and very rarely hallucinations or seizures may occur (use with caution in known or suspected CNS disorder). 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. Use of quinolones linked to peripheral neuropathy (rare). Use caution with renal impairment. Reports of tendon inflammation and/or rupture with quinolone antibiotics (risk may be increased with concurrent corticosteroids, particularly in the elderly). Some quinolones may exacerbate myasthenia gravis, use with caution (rare, potentially life-threatening weakness of respiratory muscles may occur). Use with caution in 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. Other quinolones caused transient arthropathy in children.