What the FDA labels say about taking them together
Oxacillin and probenecid
Oxacillin's FDA label of December 31, 2025 names probenecid in its drug interactions section; the probenecid label PlainMeds reads does not name oxacillin. The oxacillin label: “Oxacillin blood levels may be prolonged by concurrent administration of probenecid which blocks the renal tubular secretion of penicillins.”
Check it at the source: the oxacillin FDA label on DailyMed (effective December 31, 2025, Onesource Specialty Pharma Limited); the probenecid FDA label on DailyMed (effective January 5, 2021, Lannett Company, Inc.).
What does the oxacillin label say about probenecid?
Oxacillin label, drug interactionsOxacillin blood levels may be increased and prolonged by concurrent administration of probenecid which blocks the renal tubular secretion of penicillins.
Source: FDA drug label (Oxacillin, NDA050640), Baxter Healthcare Corporation, effective August 31, 2026 (SPL set d893e45b-7f18-4c67-b10c-1e2e52a6b3ef), via openFDA
Source: FDA drug label (oxacillin), Onesource Specialty Pharma Limited, effective December 31, 2025 (SPL set 4972ec74-1d9a-de9b-e063-6394a90af786), via openFDA; the full label on DailyMed
What does the probenecid label say about oxacillin?
Probenecid's label (effective January 5, 2021) does not name oxacillin in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Probenecid), Lannett Company, Inc., effective January 5, 2021 (SPL set ab497fd8-00c3-4364-b003-b39d21fbdf38), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Oxacillin | Probenecid | |
|---|---|---|
| Labeled for | n/a | Gout |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | n/a | $0.636 per tablet 500 mg tablet |
| Shortage now | No current entry | No current entry |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once