Oxacillin Side Effects

It is possible that some side effects of oxacillin may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

For the Consumer

Applies to oxacillin: parenteral injection, parenteral powder for injection

Side effects include:

Hypersensitivity reactions; local reactions (phlebitis, thrombophlebitis); renal, hepatic, or nervous system effects with high dosage.

For Healthcare Professionals

Applies to oxacillin: injectable powder for injection, intravenous solution, oral capsule, oral powder for reconstitution


Gastrointestinal side effects have included nausea, vomiting, diarrhea, stomatitis, black or hairy tongue, gastrointestinal irritation, and pseudomembranous colitis.


Hematologic effects of oxacillin are uncommon and appear to be associated with higher doses given for prolonged periods. Oxacillin may exert a reversible toxic effect on the maturation of granulocytes. Some investigators have also suggested a possible hypersensitivity or immunologic component. Recovery generally occurs within several days to 2 weeks following discontinuation of therapy. Penicillin and some of its other semisynthetic derivatives are also associated with hematologic toxicities.

Hematologic adverse effects have included neutropenia, leukopenia, thrombocytopenia, bone marrow depression, and agranulocytosis.


Hepatic side effects have included cholestatic jaundice associated with the use of high parenteral doses. A case of severe hepatitis has also been reported. Alkaline phosphatase and GGT serum levels may take several weeks to return to normal following discontinuation of therapy.

Serum liver enzyme levels have typically returned to normal soon after stopping therapy or changing to another antibiotic such as nafcillin, which is chemically related to oxacillin. Patients may be asymptomatic or have hepatic tenderness or enlargement and/or pronounced fever, nausea, and vomiting. Hepatotoxicity may also occur on a hypersensitivity basis and accompany some allergic manifestations such as pruritus, eosinophilia, and serum sickness.

Intravenous oxacillin has been associated with a higher incidence of hepatotoxicity than nafcillin, clindamycin, or other intravenous antimicrobials in children. The onset of hepatitis occurred after 6 to 43 days of oxacillin treatment (n=9).


Hypersensitivity reactions have included urticaria, pruritus, angioneurotic edema, laryngospasm, bronchospasm, hypotension, vascular collapse, anaphylaxis, death, serum sickness-like reactions, fever, and rash.


Local side effects of parenteral administration have included thrombophlebitis and tissue necrosis following extravasation.


Renal side effects have included acute renal failure and interstitial nephritis.

Nervous system

Nervous system side effects including seizures have occurred when large parenteral doses of oxacillin were administered to patients with renal failure.


Metabolic side effects including severe hypokalemia, have been rarely associated with the use of high dose oxacillin (12 grams per day for 10 days).


Intravenous oxacillin has been associated with a higher incidence of rash than nafcillin or other intravenous antimicrobials in children. The onset of rash occurred after a mean of 19.5 days of oxacillin treatment.

Dermatologic side effects included hypersensitivity-related urticaria, pruritus, and rash.

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