What the FDA labels say about taking them together
Oxacillin and tetracycline
Oxacillin's FDA label of December 31, 2025 names tetracycline in its drug interactions section; the tetracycline label PlainMeds reads does not name oxacillin.
Check it at the source: the oxacillin FDA label on DailyMed (effective December 31, 2025, Onesource Specialty Pharma Limited); the tetracycline FDA label on DailyMed (effective March 18, 2025, Heritage Pharmaceuticals Inc. d/b/a Avet Pharmaceuticals Inc.).
What does the oxacillin label say about tetracycline?
Oxacillin label, drug interactionsDRUG INTERACTIONS Tetracycline, a bacteriostatic antibiotic, may antagonize the bactericidal effect of penicillin and concurrent use of these drugs should be avoided.
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 tetracycline label say about oxacillin?
Tetracycline's label (effective March 18, 2025) 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 (tetracycline hydrochloride), Heritage Pharmaceuticals Inc. d/b/a Avet Pharmaceuticals Inc., effective March 18, 2025 (SPL set eaa5b1bd-0927-46e4-b941-32fcc492d258), 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 | Tetracycline | |
|---|---|---|
| Labeled for | n/a | Bacterial infections |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | n/a | $0.247 per capsule 250 mg capsule |
| 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