What the FDA labels say about taking them together
Furosemide and tobramycin
Tobramycin's FDA label (Tobi) of November 15, 2025 names furosemide in its drug interactions section; the furosemide labels PlainMeds reads (4) do not name tobramycin. The tobramycin label: “Concomitant administration with ethacrynic acid, furosemide, urea, or intravenous mannitol is not recommended due to possible enhancement of aminoglycoside toxicity.”
Check it at the source: the furosemide FDA label on DailyMed (effective September 30, 2025, Validus Pharmaceuticals LLC); the tobramycin FDA label on DailyMed (effective November 1, 2023, Bausch & Lomb Incorporated).
What does the furosemide label say about tobramycin?
Furosemide's label (effective September 30, 2025) and its 3 other brand-application labels do not name tobramycin in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Lasix), Validus Pharmaceuticals LLC, effective September 30, 2025 (SPL set 2c9b4d8f-0770-482d-a9e6-9c616a440b1a), via openFDA; the full label on DailyMed
What does the tobramycin label say about furosemide?
Tobi label (Viatris Specialty LLC, November 15, 2025), drug interactionsConcomitant administration with ethacrynic acid, furosemide, urea, or intravenous mannitol is not recommended due to possible enhancement of aminoglycoside toxicity.
Bethkis label (Chiesi USA, Inc., February 24, 2023), drug interactionsDRUG INTERACTIONS Concurrent and/or sequential use of BETHKIS with other drugs with neurotoxic, nephrotoxic or ototoxic potential should be avoided. ( 7.1 ) BETHKIS should not be administered concomitantly with ethacrynic acid, furosemide, urea, or intravenous mannitol.
Tobi Podhaler label (Viatris Specialty LLC, April 15, 2026), drug interactionsTOBI Podhaler should not be administered concomitantly with ethacrynic acid, furosemide, urea, or intravenous mannitol.
Source: FDA drug label (Tobi, NDA050753), Viatris Specialty LLC, effective November 15, 2025 (SPL set 6a3c3871-1d3a-44d6-8be3-526b30123ef7), via openFDA
Source: FDA drug label (Bethkis, NDA201820), Chiesi USA, Inc., effective February 24, 2023 (SPL set 1cd3d47b-025f-4705-9daf-cf07725ec223), via openFDA
Source: FDA drug label (Tobi Podhaler, NDA201688), Viatris Specialty LLC, effective April 15, 2026 (SPL set c4b5bb1f-e158-4ac1-9c35-e98a416c743a), via openFDA
Source: FDA drug label (Tobramycin), Bausch & Lomb Incorporated, effective November 1, 2023 (SPL set a5693ec9-d2f7-4d45-90b0-a113c54840d7), 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
| Furosemide | Tobramycin | |
|---|---|---|
| Labeled for | Heart failure, High blood pressure, Edema (fluid retention) | Bacterial infections, Urinary tract infections |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.490 per mL 20 mg/2 mL vial | $1.08 per mL 300 mg/5 mL ampule |
| Shortage now | In shortage | A presentation being discontinued |
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