Comprehensive medication guide to Polymyxin B/Trimethoprim including estimated pricing, availability information, side effects, and how to find it in stock at your local pharmacy.
Estimated Insurance Pricing
$0–$15 copay on most commercial insurance plans; typically covered as a Tier 1–2 generic. Medicare Part D generally covers it with a low copay. Medicaid coverage varies by state but is commonly included.
Estimated Cash Pricing
$12–$32 retail for a 10 mL bottle of generic polymyxin B/trimethoprim ophthalmic solution; as low as $5–$10 with GoodRx or SingleCare discount coupons at participating pharmacies.
Medfinder Findability Score
62/100
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Polymyxin B/Trimethoprim ophthalmic solution is a prescription antibiotic eye drop used to treat bacterial eye infections, including acute bacterial conjunctivitis (pink eye) and blepharoconjunctivitis. It is most commonly known by the brand name Polytrim. The FDA approved it in October 1988.
The solution combines two antibiotics in a single sterile formulation: polymyxin B sulfate (10,000 units/mL), a polypeptide antibiotic targeting gram-negative bacteria, and trimethoprim sulfate (1 mg/mL), an antifolate antibiotic that targets gram-positive bacteria. Together, they provide broad-spectrum coverage against the most common bacterial causes of eye infections.
Polymyxin B/Trimethoprim is approved for adults and children 2 months of age and older. It is available as a 10 mL sterile ophthalmic solution and is not a controlled substance. Generic versions are manufactured by Bausch Health (Bausch + Lomb) and Sandoz.
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Polymyxin B/Trimethoprim works through two distinct and complementary mechanisms of action, which is why the combination provides broader coverage than either drug alone.
Polymyxin B is a cyclic lipopeptide antibiotic that targets the outer cell membrane of gram-negative bacteria. It binds to lipopolysaccharide (LPS) in the bacterial outer membrane and disrupts its integrity — essentially punching holes in the bacterium's protective outer wall. This causes the bacterium to leak its cellular contents and die (bactericidal action). It is particularly effective against Pseudomonas aeruginosa, E. coli, K. pneumoniae, and H. influenzae.
Trimethoprim is an antifolate antibiotic that inhibits the enzyme dihydrofolate reductase (DHFR) — an enzyme bacteria require to produce folic acid. Without folic acid, bacteria cannot synthesize DNA, RNA, or the proteins needed for growth and reproduction (bacteriostatic action). Trimethoprim's binding affinity for bacterial DHFR is approximately 50,000 times stronger than for human DHFR, making it selectively toxic to bacteria without significant impact on human cells.
10,000 units/mL polymyxin B + 1 mg/mL trimethoprim — ophthalmic solution
Standard concentration; 10 mL sterile dropper bottle; 1 drop every 3 hours (max 6 doses/day) for 7–10 days
The national-level shortage of Polymyxin B/Trimethoprim — triggered by Akorn, Inc.'s closure in February 2023 — has largely resolved as of late 2024. Bausch Health and Sandoz are both actively manufacturing and distributing the product. However, pharmacy-level availability remains inconsistent. Not every pharmacy carries every manufacturer's version, and local demand spikes (particularly during winter and spring conjunctivitis season) can lead to temporary stock-outs at individual locations.
Independent pharmacies and those with diversified supplier relationships tend to have more consistent stock than chain pharmacies that source through centralized wholesalers. Patients who encounter stock-outs should try multiple pharmacies, request a special order (typically takes 24–48 hours), or ask their prescriber about switching to an available alternative such as ciprofloxacin or moxifloxacin eye drops.
The easiest way to locate this medication is to use medfinder, which calls pharmacies near you to check real-time stock and texts you the results — saving significant time over calling pharmacies individually.
Polymyxin B/Trimethoprim is not a controlled substance, so it can be prescribed by any licensed clinician with prescribing authority in their state. No specialty certification or DEA registration is required to prescribe this medication.
Ophthalmologists — Eye specialists; preferred for complex or recurrent infections
Optometrists (ODs) — Licensed to prescribe antibiotic eye drops in all 50 states; commonly the fastest in-person option
Primary Care Physicians (PCPs) — Frequently prescribe ophthalmic antibiotics for straightforward conjunctivitis
Pediatricians — Commonly manage conjunctivitis in children; Polytrim is approved for children ≥2 months
Nurse Practitioners (NPs) and Physician Assistants (PAs) — Can independently prescribe in most states; frequently seen at urgent care clinics
Urgent Care Providers — Routinely diagnose and treat bacterial conjunctivitis; walk-in availability
Telehealth is also a convenient option for uncomplicated bacterial conjunctivitis in adults and older children. Platforms such as Teladoc, MDLive, and Amazon Clinic can evaluate symptoms via video and send an electronic prescription directly to the patient's pharmacy.
No. Polymyxin B/Trimethoprim ophthalmic solution is not a controlled substance. It has no DEA scheduling designation (Schedule I through V). This means it can be prescribed by any licensed clinician — including primary care physicians, pediatricians, optometrists, nurse practitioners, and physician assistants — without the additional prescribing restrictions that apply to controlled drugs.
Prescriptions can be transmitted electronically or phoned in to any pharmacy. There are no limits on refills from a regulatory standpoint, though prescribers typically write for a single 7–10 day treatment course since this is all that is clinically needed for most bacterial eye infections.
Most side effects are mild and local to the eye:
Stinging or burning immediately after instillation (most common)
Increased redness of the eye
Itching at the site of application
Temporary blurred vision immediately after instillation
Hypersensitivity reactions: lid edema, circumocular rash, severe tearing — discontinue use and contact provider
Allergic reaction (rare): hives, swelling of face/lips/tongue/throat, difficulty breathing — seek emergency care
Fungal superinfection with prolonged use — do not exceed prescribed 7–10 day course
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Moxifloxacin (Vigamox, Moxeza)
Fourth-generation fluoroquinolone; broader spectrum and faster resolution; 1 drop TID for 7 days; more expensive than generic Polytrim
Ciprofloxacin (Ciloxan)
Fluoroquinolone; also approved for corneal ulcers; more frequent dosing; widely available generic; appropriate when corneal involvement is suspected
Ofloxacin (Ocuflox)
Older fluoroquinolone; similar to ciprofloxacin; approved for ages ≥1 year; good gram-negative coverage
Tobramycin (Tobrex)
Aminoglycoside; preferred when Pseudomonas is suspected (contact lens wearers); also available combined with dexamethasone (Tobradex)
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Other ophthalmic eye drops
minorWait at least 5 minutes between different eye drop medications to prevent washout of the prior dose. Apply ointments last.
Soft contact lenses
moderateBenzalkonium chloride preservative (0.004%) can be absorbed by soft contact lenses and damage or discolor them. Remove lenses before each dose and wait 15 minutes before reinserting.
Sulfonamide antibiotics (sulfa drugs)
moderateTrimethoprim has structural similarities to sulfonamides. Patients with known severe sulfa allergy should discuss with their provider before use — some providers prefer to prescribe an alternative.
Polymyxin B/Trimethoprim (Polytrim) is a well-established, cost-effective antibiotic eye drop that has been treating bacterial conjunctivitis since 1988. Its dual mechanism of action provides broad-spectrum coverage, its low-resistance profile makes it a responsible first-line choice, and its affordability — especially in generic form — removes financial barriers for most patients.
The supply situation has improved significantly since the 2023 disruption caused by Akorn's closure. Bausch Health and Sandoz are both producing the medication. While individual pharmacy stock can still be uneven, the drug is available and findable with the right approach. Independent pharmacies, pharmacy search tools, and special-ordering through your current pharmacy are all effective strategies.
If you're having trouble locating this medication near you, medfinder can take the legwork out of pharmacy searching — just provide your medication, dosage, and zip code, and get results texted to you.
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