Such injuries, including tendon rupture, has been observed up to 6 months after cessation of treatment; higher doses of fluoroquinolones, being elderly, transplant patients, and those with a current or historical corticosteroid use are at elevated risk. The U.S. label for levofloxacin also contains a black box warning for the exacerbation of the symptoms of the neurological disease myasthenia gravis. Similarly, the UK Medicines and Healthcare Products Regulatory Agency recommendations warn of rare but disabling and potentially irreversible adverse effects, and to recommend limiting use of these drugs. Increasing age and corticosteroid use appears to increase the risk of musculoskeletal complications.A wide variety of other uncommon but serious adverse events have been associated with fluoroquinolone use, with varying degrees of evidence supporting causation. These include anaphylaxis, hepatotoxicity, central nervous system effects including seizures and psychiatric effects, prolongation of the QT interval, blood glucose disturbances, and photosensitivity, among others. Levofloxacin may produce fewer of these rare serious adverse effects than other fluoroquinolones.There is some disagreement in the medical literature regarding whether and to what extent levofloxacin and other fluoroquinolones produce serious adverse effects more frequently than other broad spectrum antibacterial drugs.There are some case reports of levofloxacin associated with idiopathic intracranial hypertension.With regard to more usual adverse effects, in pooled results from 7537 patients exposed to levofloxacin in 29 clinical trials, 4.3% discontinued treatment due to adverse drug reactions. The most common adverse reactions leading to discontinuation were gastrointestinal, including nausea, vomiting, and constipation.
Due to potential risks to the baby, the manufacturer does not recommend that nursing mothers take levofloxacin. However, the risk appears to be very low, and levofloxacin can be used in breastfeeding mothers with proper monitoring of the infant, combined with delaying breastfeeding for 4–6 hours after taking levofloxacin. Children
Levofloxacin is not approved in most countries for the treatment of children except in unique and life-threatening infections because it is associated with an elevated risk of musculoskeletal injury in this population, a property it shares with other fluoroquinolones. In the United States levofloxacin is approved for the treatment of anthrax and plague in children over six months of age.Levofloxacin is recommended by the Pediatric Infectious Disease Society and the Infectious Disease Society of America as a first-line treatment for pediatric pneumonia caused by penicillin-resistant Streptococcus pneumoniae, and as a second-line agent for the treatment of penicillin-sensitive cases.In one study, 1534 juvenile patients (age 6 months to 16 years) treated with levofloxacin as part of three efficacy trials were followed up to assess all musculoskeletal events occurring up to 12 months post-treatment. At 12 months follow-up the cumulative incidence of musculoskeletal adverse events was 3.4%, compared to 1.8% among 893 patients treated with other antibiotics. In the levafloxacin-treated group, approximately two-thirds of these musculoskeletal adverse events occurred in the first 60 days, 86% were mild, 17% were moderate, and all resolved without long-term sequelae.