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Overview: Neomycin is an antibiotic that is used to stop normal gut bacteria from growing before surgeries and to improve brain function in people who are in a coma from liver failure. Common side effects include nausea, vomiting, and diarrhea. Serious side effects may include hearing loss, nerve damage, and kidney damage. Tell your health care provider right away if you have hearing problems, tingling, numbness, or a reduced need to pee.

Uses

What is neomycin used for?

Neomycin is an antibiotic that is commonly used to suppress normal gut bacteria in preparation for surgeries or other procedures.

Neomycin is also used to improve brain function in hepatic coma (portal-systemic encephalopathy).

Neomycin may also be used for other conditions as determined by your health care provider.

Neomycin may not be appropriate for some of the uses listed above, depending on which germs are involved. Bacteria in some locations may have developed resistance to neomycin, which will make it not work as well.

How does neomycin work (mechanism of action)?

Neomycin kills certain types of bacteria by preventing them from making proteins. For hepatic coma, neomycin works by reducing the number of bacteria in your gut that make ammonia.

How is neomycin supplied (dosage forms)?

Brands and other names

  • Mycifradin
  • Neo-Fradin

Dosage forms and strengths

  • 500 mg oral tablets

How should I store neomycin?

Neomycin should be stored at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place.

Side Effects

What are the most common side effects of neomycin?

The most common side effects of neomycin are listed below. Tell your health care provider if you have any of these side effects that bother you.

  • Nausea
  • Vomiting
  • Diarrhea

There may be other side effects of neomycin that are not listed here. Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of neomycin?

While less common, the most serious side effects of neomycin are described below, along with what to do if they happen.

Severe Allergic Reactions. Neomycin may cause allergic reactions, which can be serious. Stop taking neomycin and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Hearing Loss. Neomycin may be associated with hearing loss, which is also called ototoxicity. The risk of hearing loss is higher if neomycin is used for longer periods of time or at higher doses. The risk is also higher in people with kidney problems. You may be at a higher risk of hearing loss if your mother has a history of hearing loss with neomycin or any similar medicines. Hearing loss may be permanent. Tell your health care provider right away if you have hearing loss or if you hear a ringing or roaring sound in your ears.

Nerve Damage. Damage to nerves can happen in people who are using neomycin. Tell your health care provider if you develop symptoms of nerve damage, such as tingling or numbness. Nerve damage can also cause muscle-related symptoms such as muscle twitching, paralysis, seizures, or breathing problems.

Kidney Damage. Kidney damage can happen when taking neomycin. The risk of kidney damage is higher if neomycin is used for longer periods of time or at higher doses. The risk is also higher in people with existing kidney problems. Call your health care provider right away if you have any of the following symptoms of kidney damage.

  • Reduced need to pee
  • Swelling in your feet, ankles, or legs
  • Weakness or unusual tiredness
  • Difficulty catching your breath or chest pain/pressure
  • Confusion
  • Nausea
  • Seizures

Food Absorption Problems. Neomycin can reduce your body’s absorption of certain nutrients (malabsorption syndrome), including fats, sugars, vitamins, and minerals. Neomycin can also increase the amount of bile acid in your fecal matter (poop) and reduce the activity of an enzyme in your gut (lactase) that breaks down certain types of sugar found in milk products (lactose). Tell your health care provider if you get diarrhea or stomach problems.

Warnings & Precautions

Who should not use neomycin?

Allergies to Ingredients. People who are allergic to any of the following should not take neomycin.

  • Neo-Fradin
  • Neomycin
  • Mycifradin
  • Any other medicine known as an aminoglycoside
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific neomycin products they stock.

Gut Blockage. People with bowel obstruction should not take neomycin.

Gut Inflammation or Ulcers. People with inflammatory diseases (such as ulcerative colitis or inflammatory bowel disease) or ulcers in their gut should not take neomycin. These conditions may increase unwanted absorption of neomycin in the gut.

What should I know about neomycin before using it?

Do not take neomycin unless it has been prescribed to you by a health care provider. Take it as prescribed.

Do not share neomycin with other people, even if they have the same condition as you. It may harm them.

Keep neomycin out of the reach of children.

Neomycin only treats or prevents certain infections caused by bacteria. It will not work for infections caused by viruses, such as the common cold, the flu, or coronavirus. It also will not work for any other infections that are not caused by bacteria. Taking neomycin or any other antibiotic when it is not needed may cause the antibiotic to not work for bacterial infections in the future.

Your health care provider may instruct you to follow certain dietary restrictions before and/or while you are taking neomycin. Carefully follow all instructions.

What should I tell my health care provider before using neomycin?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if neomycin is right for you.

In particular, make sure that you discuss any of the following.

Other Medicines and Supplements. Neomycin may interact with other medicines and supplements. Before taking neomycin, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Family History. Certain genetic factors can increase your chance of developing hearing loss with neomycin. For example, if your mother had hearing problems from neomycin or a similar medicine, you may be at a higher risk for this side effect. Tell your health care provider about any family history of side effects to this type of antibiotic that you know about.

Current and Past Health Conditions. Tell your health care provider if you have any of the following.

Pregnancy. Neomycin may cause harm to an unborn baby. Tell your health care provider if you are or plan to become pregnant. Your health care provider will advise you if you should take neomycin while you are pregnant or trying to get pregnant.

Breastfeeding. It is not known if neomycin passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed. Your health care provider will advise you if you should stop breastfeeding or stop neomycin.

Interactions

Does neomycin interact with foods or drinks?

There are no known interactions between neomycin and foods or drinks.

It is unknown if drinking alcohol will affect neomycin, but heavy drinking can slow your immune response and make it harder for your body to fight infection. 

Does neomycin interact with other medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before taking neomycin.

  • A nonsteroidal anti-inflammatory drug (NSAID), such as ibuprofen, naproxen, and others, which is in many prescription and OTC products for pain, swelling, and fever
  • An aminoglycoside antibiotic, such as amikacin, gentamicin, or tobramycin, which is a medicine to treat infections
  • 5-fluorouracil (5-FU), which is a chemotherapy used to treat certain cancers
  • Penicillin V potassium, which is an antibiotic used to treat certain infections caused by bacteria
  • Methotrexate (Trexall and others), which is a medicine commonly used for rheumatoid arthritis or certain types of cancer
  • Digoxin (Lanoxin), which is a medicine used to treat irregular heartbeat and some types of heart failure
  • Warfarin, which is a blood thinner
  • Vitamin B12, which is a vitamin that may be used for some blood disorders, such as anemia

This may not be a complete list of medicines that can interact with neomycin. Always check with your health care provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much neomycin?

If you or someone else has used too much neomycin, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of neomycin?

It is important to complete your prescribed course of neomycin, even if your symptoms get better or go away. This will reduce the risk of future infections being resistant to neomycin or other similar medicines.

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.