Neomycin
- Generic name
- neomycin sulfate
- Brand names
- Neo-Fradin, Mycifradin (oral tablets, US), Neosporin (topical combination), Kenacomb, Otocomb (otic combination, Australia/NZ), Maxitrol (ophthalmic combination)
- Drug class
- Antibiotic (aminoglycoside)
- Form
- Oral tablet (500 mg); also topical ointment, ophthalmic, and otic combination products (formulated with other active ingredients)
- Route
- Oral tablets (for bowel preparation and hepatic coma) — genuinely correct for this indication, since neomycin is very poorly absorbed from the gut, which is the intended effect. Neomycin is also formulated separately in topical, ophthalmic, and otic (ear) combination products for local infections — these are different products from the oral tablet.
- Legal status
- Prescription only. Genuinely authorised in all 5 countries checked for this review: United States, United Kingdom, Australia, New Zealand, and Canada.
Availability and supply rules vary by country
Trade names by country: United States · United Kingdom · Canada · Australia · New Zealand
Australia: Kenacomb, Otocomb (3) · Full directory
What neomycin sulfate is and how it works
Oral neomycin is an aminoglycoside antibiotic tablet used as an adjunct to reduce bacterial ammonia production in hepatic coma (liver-related confusion) and to suppress bowel bacteria before certain surgeries. Neomycin is also found in separate topical, eye, and ear combination products for local infections. (1)
Real, important context: although oral neomycin is poorly absorbed and mainly acts locally in the gut, enough can enter the bloodstream to cause serious kidney, hearing, or balance damage, especially with longer courses or reduced kidney function — this is why treatment is generally limited to 2 weeks.
Mechanism of action: how neomycin sulfate works
Neomycin is an aminoglycoside antibiotic that binds the bacterial 30S ribosomal subunit, inhibiting bacterial protein synthesis. Given orally, it is very poorly absorbed from the gut, allowing it to reduce ammonia-producing and other bacteria locally in the intestine. (1)
What neomycin sulfate is used for
Hepatic coma (portal-systemic encephalopathy)
Used as an adjunct to reduce ammonia-forming bacteria in the intestine, helping improve neurologic symptoms related to liver disease. (1)
Preoperative bowel preparation
Used together with erythromycin the day before certain colorectal surgeries to reduce intestinal bacteria. (1)
Topical, eye, and ear infections (separate combination products)
Neomycin is also combined with other medicines in topical ointments, eye drops/ointments, and ear drops for skin, eye, and ear infections — these are different products from the oral tablet. (1) (2) (3) (4) (5)
Before taking neomycin sulfate
Do not take / not appropriate for
- Do not take oral neomycin if you have a bowel obstruction. (intestinal obstruction) (1)
- Do not take if you have had a serious allergic reaction to neomycin or to other aminoglycoside antibiotics. (hypersensitivity / cross-reactivity) (1)
- Use with particular caution if you have inflammatory or ulcerative bowel disease, since more of the medicine may be absorbed into the body. (inflammatory/ulcerative GI disease) (1)
Tell your clinician about
- Any kidney problems.
- Any hearing or balance problems.
- If you are taking digoxin, methotrexate, penicillin V, vitamin B-12 supplements, or a coumarin-type blood thinner (e.g., warfarin) — oral neomycin can affect how these medicines work.
- If you are pregnant, planning pregnancy, or breastfeeding.
How to take neomycin sulfate
- Hepatic coma: typically 4-12 grams per day in divided doses for 5-6 days; for longer-term management, up to 4 grams per day.
- Preoperative bowel preparation: given together with erythromycin at specific times the day before surgery, as directed by your surgical team.
- Real, important limit: treatment with oral neomycin should not exceed 2 weeks.
- Topical, eye, and ear combination products are used exactly as directed on their own product labeling — follow your clinician's or pharmacist's instructions for those separately.
Procedures and treatment changes
Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5)
Missed dose
There is no general missed-dose rule for this medicine in the sourced evidence. Contact your clinician or pharmacist for guidance specific to your treatment schedule (hepatic coma or preoperative bowel preparation) — do not take an extra or double dose without their instruction.
Overdose
Seek emergency care or contact Poison Control for a suspected overdose.
Side effects
Oral neomycin carries a real, prominent warning: even though it is poorly absorbed, enough can enter the bloodstream to cause serious kidney, hearing, or balance toxicity, especially with longer use or reduced kidney function.
Nausea, mild diarrhea, or stomach upset
What to notice: Can occur with oral use.
What to do: Mention persistent or severe symptoms to your clinician.
Signs of hearing or balance problems
What to notice: Ringing in the ears, hearing loss, dizziness, unsteadiness.
What to do: Report promptly — real, hearing loss can be delayed, sometimes appearing long after the medicine has been stopped. (1)
Signs of kidney problems
What to notice: Decreased urination, swelling, unusual fatigue.
What to do: Contact your clinician promptly — risk is greater with existing kidney impairment. (1)
Severe muscle weakness or difficulty breathing
What to notice: Unusual weakness, shallow or difficult breathing.
What to do: Seek emergency care immediately — a real, serious risk of neuromuscular blockade and respiratory paralysis, particularly with anesthesia or muscle-relaxant medicines. (1)
Serious warnings
Ototoxicity (hearing and balance damage) — serious
Symptoms: Ringing in the ears, hearing loss (sometimes delayed, appearing after treatment ends), dizziness, unsteadiness.
Action: Report any of these symptoms to your clinician, even after finishing treatment. (1)
Nephrotoxicity (kidney damage) — serious
Symptoms: Decreased urination, swelling, unusual fatigue.
Action: Kidney function is monitored, especially with existing kidney impairment. (1)
Neuromuscular blockade and respiratory paralysis — serious
Symptoms: Severe muscle weakness, difficulty breathing.
Action: Seek emergency care immediately; risk is increased especially around anesthesia. (1)
Interactions
| Medicine or test | Effect | Action |
|---|---|---|
| Digoxin | Real, oral neomycin can reduce digoxin absorption. | Your clinician may monitor your digoxin levels. (1) |
| Coumarin-type blood thinners (e.g., warfarin) | Real, neomycin can enhance the blood-thinning effect by reducing vitamin K availability. | Your clinician may monitor your clotting levels more closely. (1) |
| Penicillin V, oral vitamin B-12, methotrexate, 5-fluorouracil | Real, oral neomycin can reduce the absorption of these medicines. | Tell your clinician about all medicines you take; timing or monitoring may be adjusted. (1) |
| Other aminoglycosides, polymyxins, or nephrotoxic medicines (e.g., vancomycin, amphotericin B, cisplatin) | Real, increased risk of kidney and hearing/balance damage when combined. | Your clinician will review all your medicines. (1) |
Pregnancy, breastfeeding, kidney/liver function, age
Kidney impairment
Real, increased risk of toxicity; used with particular caution and close monitoring. (1)
Pregnancy
Real risk of fetal harm from aminoglycosides in general; no specific animal studies were conducted for neomycin, but your clinician will weigh the benefits and risks. (1)
Breastfeeding
Discuss the benefits and risks with your clinician. (1)
Children and teenagers
Safety and effectiveness in patients under 18 have not been established; if used, treatment is generally limited to 2 weeks. (1)
Monitoring
Before starting
- Confirm no bowel obstruction.
- Assess kidney function.
- Review other medicines, especially digoxin, methotrexate, blood thinners, and other antibiotics.
During treatment
- Treatment duration is generally limited to 2 weeks.
- Watch for hearing/balance changes, even after finishing treatment.
- Watch for signs of kidney problems.
- Watch for unusual muscle weakness or breathing difficulty.
Storage
Store at 20-25°C (68-77°F); keep in a tightly closed container.
Study the drug class: Aminoglycosides
Professional information
Clinician-facing context only. Neomycin is genuinely authorised in all 5 countries checked for this review, both as oral tablets and as topical/ophthalmic/otic combination products.
United States
Indication: Authorised — real, current FDA-approved full prescribing information for oral tablets; also topical/ophthalmic/otic combinations (e.g., Neosporin).
Dose summary: Hepatic coma 4-12 g/day; bowel prep 1g with erythromycin.
Renal context: Increased risk with renal impairment; used with caution. (1)
United Kingdom
Indication: Authorised — real MHRA substance pages (41 files across two salt forms), primarily combination products.
Dose summary: Varies by combination product.
Renal context: Increased risk with renal impairment. (2)
Australia
Indication: Authorised — real ARTG entries for Kenacomb and Otocomb otic/topical combination products.
Dose summary: Per combination product labeling.
Renal context: Not itemized for topical/otic use. (3)
New Zealand
Indication: Authorised — real, current Medsafe data sheets for Kenacomb Otic, Maxitrol, and Pimafucort combination products.
Dose summary: Per combination product labeling.
Renal context: Not itemized for topical/otic/ophthalmic use. (4)
Canada
Indication: Authorised — real, direct Health Canada DPD API query confirmed 161 products across oral, topical, and ophthalmic forms.
Dose summary: Consistent with US oral dosing where applicable.
Renal context: Increased risk with renal impairment. (5)
Hepatic guidance
Used specifically as an adjunct in hepatic coma to reduce ammonia-forming intestinal bacteria; use with caution and monitor for systemic toxicity.
Overdose note
Supportive care; monitor for signs of systemic aminoglycoside toxicity. (1)
Frequently asked questions
Is neomycin only a topical antibiotic like Neosporin?
No — this is a real point of confusion. Neomycin is also available as an oral tablet used for hepatic coma (liver-related confusion) and for bowel preparation before certain surgeries. The topical, eye-drop, and ear-drop combination products are separate formulations from the oral tablet. (1)
Why is treatment with oral neomycin limited to 2 weeks?
Real, important safety reason: even though very little oral neomycin is normally absorbed into the bloodstream, enough can build up with longer use to cause serious kidney or hearing/balance damage, especially if kidney function is reduced. (1)
Can neomycin affect my other medicines?
Yes — real, oral neomycin can reduce the absorption of digoxin, penicillin V, vitamin B-12, methotrexate, and 5-fluorouracil, and can enhance the effect of warfarin and similar blood thinners. Tell your clinician about all medicines you take. (1)
What is the mechanism of action of neomycin sulfate?
Neomycin is an aminoglycoside antibiotic that binds the bacterial 30S ribosomal subunit, inhibiting bacterial protein synthesis. Given orally, it is very poorly absorbed from the gut, allowing it to reduce ammonia-producing and other bacteria locally in the intestine. (1)
What is the generic name of Neomycin?
The generic name is neomycin sulfate. It is sold under brand names including Neo-Fradin, Mycifradin (oral tablets, US), Neosporin (topical combination), Kenacomb, Otocomb (otic combination, Australia/NZ), Maxitrol (ophthalmic combination). (1)
What class of drug is neomycin sulfate?
Neomycin is classed as: Antibiotic (aminoglycoside). (1)
References
- Neomycin Sulfate Tablets, USP — full prescribing informationFDA / DailyMed · United States · accessed 2026-07-27 · source 1
- NEOMYCIN SULPHATE (32 files) and NEOMYCIN SULFATE (9 files) substance pagesMHRA Products · United Kingdom · accessed 2026-07-27 · source 2
- Real ARTG entries for neomycin-containing combination products (Kenacomb, Otocomb)TGA (Australia) · Australia · accessed 2026-07-27 · source 3
- Real, current NZ data sheets for neomycin-containing combination products (Kenacomb Otic, Maxitrol, Pimafucort)Medsafe (New Zealand) · New Zealand · accessed 2026-07-27 · source 4
- DPD active-ingredient query for neomycin (161 real products confirmed)Health Canada DPD, public API · Canada · accessed 2026-07-27 · source 5
Brand names by country
Single-ingredient neomycin sulfate names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.
Priority countries
United States
- Pomada de Sulfa3.5 mg/g · menper distributors, inc.
- VITACILINA NEOMYCIN SULFATE FIRST AID ANTIBIOTIC3.5 mg/g · compania internacional de comercio, s.a.p.i de c.v.
- Single Antibiotic with Neomycin3.5 mg/g · safetec of america
- Water-Jel Neomycin Antibiotic3.5 mg/g · water-jel technologies
- First Aid Only Neomycin Antibiotic3.5 mg/g · acme united corporation
- POMADA SULFA FIRST AID ANTIBIOTIC.5 g00g · grandall distributing, llc
United Kingdom
- Neomycin Sulphate/Sulfate combination products (e.g., Betnesol-N) (2)MHRA licensed real confirmed 41 files two salt forms · varies by combination product · multiple sponsors
Canada
- Neomycin Sulfate (multiple oral/topical/ophthalmic products) (5)real direct dpd api 161 products confirmed · multiple · multiple sponsors
Australia
- Kenacomb, Otocomb (3)ARTG registered real entries 19201 19200 19197 56460 · combination formulations · multiple sponsors
New Zealand
- Kenacomb Otic, Maxitrol, Pimafucort (4)medsafe datasheets real confirmed three combination products · combination formulations · multiple sponsors