Floxacillin (Adverse effects)

Floxacillin is an antibiotic of the penicillin family used in the treatment of Gram-positive bacterial infections. Liver toxicity is one of the most serious adverse effects associated with the drug and certain genetic polymorphisms can increase the risk of presenting it.

Floxacillin or flucloxacillin is an antibiotic widely used in Europe and Australia for treating staphylococcal infections. It is a narrow-spectrum beta-lactam antibiotic of the penicillin class. It is used to treat infections caused by susceptible Gram-positive bacteria. Flucloxacillin is very similar to dicloxacillin; they are considered interchangeable.

Approximately 1 of every 10,000 persons who take this drug experience hepatic toxicity which in additional may be potentially fatal. Given that there are medicines that are not associated with these adverse side effects, floxacillin is not commercially available in the United States, nor in Spain.


  • Floxil®
  • Floxapen®
  • Flucinal®


Obstructive jaundice may appear with less frequency during flucloxacillin treatment. The reaction may appear even several weeks after terminating the treatment. The incidence of this reaction is approximately 1 in 15,000 patients treated with this medicine, especially frequent in persons older than 55 years of age, women and those who take the medicine longer than two weeks.

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