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Cloxacillin Side Effects

Medically reviewed by Last updated on May 14, 2023.

Applies to cloxacillin: oral capsule, oral powder for reconstitution.


Common gastrointestinal complaints include nausea, vomiting, and diarrhea. Rarely the use of cloxacillin has been associated with pseudomembranous colitis.[Ref]


Hematologic adverse effects include neutropenia, leukopenia, and thrombocytopenia. Neutropenia has occurred in 17% of patients and occurs most commonly with higher doses and longer durations of therapy. Neutropenia occurs most often after 14 days of therapy and is reversible upon discontinuation.[Ref]


Hepatic side effects include transient increases in serum transaminases and the development of cholestatic hepatitis. Liver transaminases may take several weeks to return to normal following discontinuation of therapy. Frequent monitoring of liver function tests is recommended in patients with liver disease.[Ref]


Hypersensitivity reactions include rash, fever, eosinophilia, pruritus, fever, chills, and myalgias.[Ref]


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7. Olsson R, Wiholm BE, Sand C, Zettergren L, Hultcrantz R, Myrhed M. Liver damage from flucloxacillin, cloxacillin and dicloxacillin. J Hepatol. 1992;15:154-61.

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Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.