IDENTIFICATION AND USE: Neomycin is used for reducing bacteria in the intestines. It may also be used for other conditions as determined by your doctor. Neomycin is an aminoglycoside antibiotic. It kills sensitive bacteria by stopping the production of essential proteins needed by the bacteria to survive.


  • you are allergic to any ingredient in neomycin or to any other aminoglycosides (eg, gentamicin)
  • you are taking fludarabine, nondepolarizing muscle relaxants (eg, vecuronium), or penicillin
  • you have intestinal obstruction, ulcers of the bowel, or inflammatory bowel or stomach disease

HUMAN EXPOSURE AND TOXICITY: Neomycin may cause permanent hearing loss, nerve damage, and severe kidney damage. Hearing loss can occur even after the drug is stopped. If you already have kidney problems or hearing difficulty, tell your doctor. Notify your doctor immediately if any of the following occur: ringing in your ears, hearing loss, unusual tingling, muscle twitching, seizures. Neomycin may be stopped if you develop kidney or hearing problems. Your doctor will monitor your progress to minimize the possibility of these effects occurring and may run certain tests (eg, hearing and/or kidney tests). Do not use neomycin with other medicines that can cause nerve, kidney, or hearing problems. Other factors that increase the risk of these side effects occurring include advanced age or dehydration (unusual thirst).

Neomycin may also cause severe muscle relaxation progressing to paralysis and breathing problems. This possibility increases if you are also taking anesthetics, neuromuscular-blocking agents (eg, succinylcholine), or if you are receiving massive transfusions of citrate anticoagulated blood. Use with other aminoglycosides (eg, paromomycin) or other nephrotoxic/neurotoxic medicines (eg, bacitracin), advanced age, and dehydration all increase the risk of side effects. Potent diuretics (eg, ethacrynic acid, furosemide) should also be avoided because they can cause hearing loss.

ADVERSE EFFECTS: some neomycin side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear.

MINOR SIDE EFFECTS: irritation or soreness of the mouth/rectal area, nausea or vomiting.

MAJOR SIDE EFFECTS: any loss of hearing, clumsiness, diarrhea, difficulty in breathing, dizziness, drowsiness, greatly decreased frequency of urination or amount of urine, increased amount of gas, increased thirst, light-colored, frothy, fatty-appearing stools, ringing or buzzing or a feeling of fullness in the ears, skin rash, unsteadiness, weakness.

RENAL SIDE EFFECTS: The major renal side effect of oral neomycin is nephrotoxicity, which has occurred even at recommended doses and in patients with normal renal function.

Early signs of nephropathy include mild proteinuria, sloughing of renal tubular epithelial cells, formation of cellular casts, and decreases in creatinine clearance. Often there is a high output renal failure where daily urine volume may appear unchanged until significant increases in serum creatinine and BUN levels occur.

Neomycin damages renal tubules by causing tubular epithelial cell necrosis. It is considered the most nephrotoxic aminoglycoside.

NERVOUS SYSTEM SIDE EFFECTS: early symptoms of neomycin-induced auditory toxicity may manifest as high tone hearing loss, tinnitus, or a feeling of fullness in the ear, or its onset may be asymptomatic. If ototoxicity occurs, the onset of hearing loss is between several days to 6 weeks after therapy begins; however, it may not occur for months or years after neomycin has been discontinued. Symptoms of vestibulotoxicity may include tinnitus, vertigo and ataxia.

Neomycin is considered more ototoxic than vestibulotoxic. It progressively accumulates in the inner ear and which leads to sensory hair cell loss in the in the cochlea and damage to the stria vascularis. In an animal study, neomycin was found to be more ototoxic than gentamicin, kanamycin and dihydrostreptomycin.

One case report series describes 5 cases of hearing impairment associated with long-term oral neomycin therapy for hepatic encephalopathy. Doses ranged from 2 to 12 g/day and were administered for 8 to 28 months; in 2 cases paromomycin was also administered. Renal failure did not occur.

Nervous system side effects associated with oral neomycin therapy have included neuromuscular blockade, respiratory paralysis, and eighth cranial nerve damage with hearing loss, even at recommended doses and in patients with normal renal function. Symptoms of neurotoxicity include numbness, tingling, muscle twitching, and convulsions.[Ref]

OTHER SIDE EFFECTS: oral neomycin therapy may result in overgrowth of nonsusceptible organisms, especially fungi. A case of fatal Candida albicans pyelonephritis and septicemia following preoperative bowel preparation with oral neomycin and bacitracin has been reported.

GASTROINTESTINAL SIDE EFFECTS: most commonly include nausea, vomiting and diarrhea. Clostridium difficile colitis has also been reported with oral neomycin therapy.