Generic name: gentamicin (GEN ta MYE sin)
Brand name: Garamycin, Cidomycin, Septopal (obsolete)
Dosage forms: injectable solution (10 mg/mL; 40 mg/mL); intravenous solution (100 mg/100 mL-0.9%; 100 mg/50 mL-0.9%; 120 mg/100 mL-0.9%; 60 mg/50 mL-0.9%; 70 mg/50 mL-0.9%; 80 mg/100 mL-0.9%; 80 mg/50 mL-0.9%; 90 mg/100 mL-0.9%)
Drug class: Aminoglycosides

Gentamicin is an antibiotic that fights bacteria.

Gentamicin is used to treat severe or serious bacterial infections.

Gentamicin may also be used for purposes not listed in this medication guide.


Gentamicin can harm your kidneys, and may also cause nerve damage or hearing loss, especially if you have kidney disease or use certain other medicines.

Tell your doctor about all your medical conditions and all the medicines you are using. If you need surgery, tell the surgeon ahead of time that you are using gentamicin.

Before taking this medicine

You should not use gentamicin if you are allergic to gentamicin or similar antibiotics such as amikacin, kanamycin, neomycin, paromomycin, streptomycin, or tobramycin.

To make sure gentamicin is safe for you, tell your doctor if you have:

  • kidney disease;
  • asthma or sulfite allergy;
  • myasthenia gravis;
  • a nerve-muscle disorder;
  • a nervous system disorder such as Parkinson's disease;
  • an electrolyte imbalance (low levels of calcium, potassium, or magnesium in your blood); or
  • if you are dehydrated.

Do not use gentamicin if you are pregnant. It could harm the unborn baby. Use effective birth control to prevent pregnancy during treatment.

It is not known whether gentamicin passes into breast milk or if it could harm a nursing baby. You should not breast-feed while using this medicine.

How should I take gentamicin?

Follow all directions on your prescription label. Do not use this medicine in larger or smaller amounts or for longer than recommended. Gentamicin is usually given for 7 to 10 days.

Gentamicin is injected into a muscle, or into a vein through an IV. You may be shown how to use an IV at home. Do not self-inject this medicine if you do not understand how to give the injection and properly dispose of used needles, IV tubing, and other items used to inject the medicine.

Do not use gentamicin if it has changed colors or has particles in it. Call your pharmacist for new medication.

Do not mix gentamicin with other medicines in a syringe or IV bag.

Use a disposable needle and syringe only once. Follow any state or local laws about throwing away used needles and syringes. Use a puncture-proof "sharps" disposal container (ask your pharmacist where to get one and how to throw it away). Keep this container out of the reach of children and pets.

Use this medicine for the full prescribed length of time. Your symptoms may improve before the infection is completely cleared. Skipping doses may also increase your risk of further infection that is resistant to antibiotics. Gentamicin will not treat a viral infection such as the flu or a common cold.

Drink plenty of liquids while you are taking gentamicin. This will help keep your kidneys working properly.

While using gentamicin, you may need frequent blood or urine tests. Your hearing, kidney function, and nerve function may also need to be checked.

If you need surgery, tell the surgeon ahead of time that you are using gentamicin.

Store this medicine at room temperature away from moisture and heat.

Detailed Gentamicin dosage information

What happens if I miss a dose?

Call your doctor for instructions if you miss a dose of gentamicin.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while taking gentamicin?

Antibiotic medicines can cause diarrhea, which may be a sign of a new infection. If you have diarrhea that is watery or bloody, call your doctor. Do not use anti-diarrhea medicine unless your doctor tells you to.

Gentamicin side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

  • hearing loss, or a roaring sound in your ears;
  • severe or ongoing dizziness;
  • weak or shallow breathing;
  • numbness or tingly feeling;
  • twitching, muscle tightness or contraction;
  • seizure (convulsions);
  • severe stomach pain, diarrhea that is watery or bloody;
  • fever, blisters or ulcers in your mouth, red or swollen gums, trouble swallowing;
  • kidney problems--little or no urinating; painful or difficult urination; swelling in your feet or ankles; feeling tired or short of breath;
  • signs of an electrolyte imbalance--confusion, weakness, bone pain, increased urination; or
  • increased pressure inside the skull--severe headaches, ringing in your ears, dizziness, nausea, vision problems, pain behind your eyes.

Side effects may be more likely in older adults.

Common side effects may include:

  • vision problems;
  • nausea, vomiting, loss of appetite, weight loss;
  • a light-headed feeling, like you might pass out;
  • itching or rash;
  • pain where the medicine was injected;
  • headache, mood changes; or
  • joint pain.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect gentamicin?

Gentamicin can harm your kidneys. This effect is increased when you also use certain other medicines, including: antivirals, chemotherapy, injected antibiotics, medicine for bowel disorders, medicine to prevent organ transplant rejection, injectable osteoporosis medication, and some pain or arthritis medicines (including aspirin, Tylenol, Advil, and Aleve).

Tell your doctor about all your current medicines and any you start or stop using, especially:

  • a diuretic or "water pill"; or
  • any other antibiotic.

This list is not complete. Other drugs may interact with gentamicin, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.