Disrupts the outer membrane of gram-negative bacteria by binding to lipopolysaccharide (LPS) and phospholipids, increasing membrane permeability and causing cell death. Used primarily topically or for MDR gram-negative infections.
At a glance
Class
Polypeptide Antibiotic
Storage
Refrigerate reconstituted solution; store powder at room temperature
Dosing
Systemic use reserved for multidrug-resistant gram-negative infections (last res
Frequency
q12h (systemic); q6–8h (topical)
Systemic use avoided in cats due to high nephrotoxicity risk
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet.
Find a vet near you →Safety
Renal function with systemic useNeurological signs
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet.
Find a vet near you →Interactions
No documented interactions.
FAQs
Frequently asked questions
›What is Polymyxin B?
Polymyxin B is a polypeptide antibiotic used in pets. Disrupts the outer membrane of gram-negative bacteria by binding to lipopolysaccharide (LPS) and phospholipids, increasing membrane permeability and causing cell death. Used primarily topically or for MDR gram-negative infections.
›What is Polymyxin B used for in pets?
Polymyxin B is used in veterinary medicine for: Systemic use reserved for multidrug-resistant gram-negative infections (last res; Systemic use avoided in cats due to high nephrotoxicity risk.
›What is the Polymyxin B dose for dogs?
For dogs, Polymyxin B is typically dosed as follows — Systemic use reserved for multidrug-resistant gram-negative infections (last res: 1.5–2.5 mg/kg Topical/IV q12h (systemic); q6–8h (topical). Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
›What is the Polymyxin B dose for cats?
For cats, Polymyxin B is typically dosed as follows — Systemic use avoided in cats due to high nephrotoxicity risk: undefined undefined Topical q6–8h. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
›Does Polymyxin B need a prescription?
Yes. Polymyxin B is a prescription medication and should only be administered under veterinary supervision.
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet.
Find a vet near you →References
References
The PetCare.AI drug reference is built from 13 authoritative sources cited across 580 drug monographs.
Textbooks & handbooks — 5
- Plumb's Veterinary Drug Handbook
- Withrow & MacEwen's Small Animal Clinical Oncology
- Merck Veterinary Manual
- NRC Nutrient Requirements of Dogs and Cats
- Veterinary Pharmacology and Therapeutics (Riviere & Papich)
Clinical guidelines & consensus — 4
- ASPCA Animal Poison Control Center Guidelines
- AAHA Diabetes Management Guidelines
- ASPCA Poison Control Guidelines
- RECOVER CPR Guidelines
Journals & peer-reviewed studies — 2
- EPIC Study (J Vet Intern Med 2016)
- JVIM FAT CAT Study
Regulatory & approvals — 1
- CDSCO Veterinary Drug Approval Registry (1969–2026)
Databases — 1
- Washington State University VCPL MDR1 Database