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What the label lists and what reports show

Oxacillin side effects

Oxacillin's FDA label lists its adverse reactions in its own words. FAERS holds 1,116 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is drug reaction with eosinophilia and systemic symptoms (68 reports).

  • Generic listed

Check it at the source: the oxacillin FDA label on DailyMed (effective December 31, 2025, Onesource Specialty Pharma Limited); the FDA FAERS public dashboard.

What does the label list?

From the label: adverse reactions

Body as a Whole The reported incidence of allergic reactions to penicillin ranges from 0.7 to 10 percent (see WARNINGS ). Sensitization is usually the result of treatment but some individuals have had immediate reactions when first treated. In such cases, it is thought that the patients may have had prior exposure to the drug via trace amounts present in milk and vaccines. Two types of allergic reactions to penicillins are noted clinically, immediate and delayed. Immediate reactions usually occur within 20 minutes of administration and range in severity from urticaria and pruritus to angioneurotic edema, laryngospasm, bronchospasm, hypotension, vascular collapse and death. Such immediate anaphylactic reactions are very rare (see WARNINGS ) and usually occur after parenteral therapy but have occurred in patients receiving oral therapy. …

Source: FDA drug label, Onesource Specialty Pharma Limited, effective December 31, 2025 (SPL set 4972ec74-1d9a-de9b-e063-6394a90af786), via openFDA; the full label on DailyMed

What do FAERS reports show?

1,116 reports list oxacillin among the medicines taken, each a report of something that happened, not proof the medicine caused it; 214 are coded as a death and 599 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 18 reactions below, 4 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.

Reports received each year

The 25 most reported reactions

  • Drug Ineffective (a use or a product term, not a reaction)92
  • Drug Reaction With Eosinophilia And Systemic Symptoms68
  • Acute Kidney Injury63
  • Pyrexia59
  • Rash (named in the label)55
  • Off Label Use (a use or a product term, not a reaction)45
  • Drug Interaction (a use or a product term, not a reaction)42
  • Toxic Epidermal Necrolysis42
  • Pneumonia41
  • Renal Failure40
  • Staphylococcal Infection (a use or a product term, not a reaction)39
  • Diarrhoea (named in the label)32
  • Alanine Aminotransferase Increased31
  • Thrombocytopenia31
  • Hypotension (named in the label)30
  • Condition Aggravated (a use or a product term, not a reaction)29
  • Eosinophilia (named in the label)29
  • Infection (a use or a product term, not a reaction)29
  • Renal Failure Acute29
  • Drug Resistance28
  • Product Use In Unapproved Indication (a use or a product term, not a reaction)27
  • Toxicity To Various Agents27
  • Aspartate Aminotransferase Increased26
  • Neutropenia26
  • Septic Shock26

Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms

What next?

Oxacillin: the full record
label, generics, price, shortages, recalls
Side effects hub
the most reported medicines and reactions