Nafcillin Side Effects

It is possible that some side effects of nafcillin 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 nafcillin: 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 nafcillin: injectable powder for injection, intravenous solution, oral capsule


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


Local side effects have included pain, swelling, phlebitis, thrombophlebitis, and skin sloughing after intravenous administration. Intramuscular injections may cause pain at the injection site. Extravasation may result in severe chemical irritation. Subcutaneous extravasation has been associated with severe tissue necrosis.


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


Hematologic side effects have included agranulocytosis, neutropenia, bone marrow depression, and platelet dysfunction. These reactions are usually reversible upon discontinuation of nafcillin.

At least three cases of platelet dysfunction with prolonged bleeding times have been reported with nafcillin therapy. All cases resolved following discontinuation of nafcillin.


Renal side effects have included renal tubular damage and interstitial nephritis. Symptoms may include rash, fever, eosinophilia, hematuria, proteinuria, and renal insufficiency.


Hepatic adverse effects are rare, but cases of hepatotoxicity associated with nafcillin therapy have been reported.

Nervous system

Nervous system side effects have included neurotoxicity with high intravenous or intraventricular doses, especially in patients with both hepatic and renal impairment.

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