What the FDA labels say about taking them together
Polymyxin b and streptomycin
Polymyxin b's FDA label of May 9, 2025 names streptomycin in its boxed warning section, and streptomycin's label names polymyxin b too.
Check it at the source: the polymyxin b FDA label on DailyMed (effective May 9, 2025, Gland Pharma Limited); the streptomycin FDA label on DailyMed (effective January 21, 2026, XGen Pharmaceuticals DJB, Inc.).
What does the polymyxin b label say about streptomycin?
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
What does the streptomycin label say about polymyxin b?
Streptomycin label, boxed warningTHE CONCURRENT OR SEQUENTIAL USE OF OTHER NEUROTOXIC AND/OR NEPHROTOXIC DRUGS WITH STREPTOMYCIN SULFATE, INCLUDING NEOMYCIN, KANAMYCIN, GENTAMICIN, CEPHALORIDINE, PAROMOMYCIN, VIOMYCIN, POLYMYXIN B, COLISTIN, TOBRAMYCIN AND CYCLOSPORINE SHOULD BE AVOIDED.
Source: FDA drug label (Streptomycin), XGen Pharmaceuticals DJB, Inc., effective January 21, 2026 (SPL set abd1f64e-4283-4370-aae8-3666316aa36e), 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
| Polymyxin b | Streptomycin | |
|---|---|---|
| Labeled for | Bacterial infections, Urinary tract infections | n/a |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | n/a | 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