What the FDA labels say about taking them together
Neomycin and polymyxin b
Neomycin's FDA label of February 12, 2026 names polymyxin b in its boxed warning (prescription label) section, and polymyxin b's label names neomycin too. The neomycin label: “… neurotoxic drugs such as bacitracin, cisplatin, vancomycin, amphotericin B, polymyxin B, colistin and viomycin, should be avoided because the toxicity may be additive.”
Check it at the source: the neomycin FDA label on DailyMed (effective February 12, 2026); the polymyxin b FDA label on DailyMed (effective May 9, 2025, Gland Pharma Limited).
What does the neomycin label say about polymyxin b?
Neomycin label, boxed warning (prescription label)Concurrent and/or sequential systemic, oral or topical use of other aminoglycosides, including paromomycin and other potentially nephrotoxic and/or neurotoxic drugs such as bacitracin, cisplatin, vancomycin, amphotericin B, polymyxin B, colistin and viomycin, should be avoided because the toxicity may be additive.
Source: FDA drug label (Neomycin Sulfate), Aldermed Inc., effective February 12, 2026 (SPL set 4978bb06-8b7c-9a44-e063-6294a90ac4cf), via openFDA; the full label on DailyMed
What does the polymyxin b label say about neomycin?
Polymyxin b label, boxed warningTHE CONCURRENT OR SEQUENTIAL USE OF OTHER NEUROTOXIC AND/OR NEPHROTOXIC DRUGS WITH POLYMYXIN B SULFATE, PARTICULARLY BACITRACIN, STREPTOMYCIN, NEOMYCIN, KANAMYCIN, GENTAMICIN, TOBRAMYCIN, AMIKACIN, CEPHALORIDINE, PAROMOMYCIN, VIOMYCIN, AND COLISTIN SHOULD BE AVOIDED.
Source: FDA drug label (POLYMYXIN B), Gland Pharma Limited, effective May 9, 2025 (SPL set dc74dee2-1d0b-4fab-a29b-1755fdb5da75), 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
| Neomycin | Polymyxin b | |
|---|---|---|
| Labeled for | n/a | Bacterial infections, Urinary tract infections |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $0.833 per tablet 500 mg tablet | n/a |
| 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