Gentamicin belongs to the family of medications known as antibiotics. It is used to treat infections of the eye or ear that are caused by certain bacteria. It works by blocking the metabolism of the bacteria and this then kills the bacteria.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. As well, some forms of this medication may not be used for all of the conditions discussed here. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

Eye drops: The usual recommended dose is 2 drops into the affected eye 3 or 4 times daily or as directed by your doctor. More frequent dosing may be used in certain situations, such as treating eye ulcers.

Eye ointment: Apply a thin film to the affected area 3 or 4 times daily or as directed by your doctor. If eye drops are used during the day, the ointment can be used at bedtime to continue treatment during the night.

Ear drops: Thoroughly clean the ear canal of wax and debris. Instill 3 or 4 drops into the affected ear 3 times daily or as directed by your doctor. Lie with the affected ear turned upward. Instill the solution and remain in this position for several minutes to ensure the medication reaches the ear canal.

If you wear soft contact lenses, do not wear them during treatment.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to use this medication exactly as prescribed by your doctor. Use it for the full duration of the prescribed treatment even if the area starts to look or feel better. If you forget a dose of this medication, use it as soon as you remember. If it is almost time for your next dose, skip the missed dose and carry on with your regular schedule. Do not use a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

This medication is available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms listed here. The forms available for the specific brand you have searched are listed under "What form(s) does this medication come in?"

Do not use this medication if you are:

• allergic to gentamicin or any ingredients of the medication.

Do not use the ear drops if you have absent or perforated ear drums.

Do not use the eye preparations if you wear contact lenses (as with all eye preparations containing benzalkonium chloride, those using the drops should not wear soft contact lenses during treatment).

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• burning or stinging sensation
• irritation

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• ringing in ears, hearing loss, or vertigo (ear drops)

Stop taking the medication and seek immediate medical attention if any of the following occur:

• itching, redness, swelling, or other sign of irritation not present before use of this medicine
• redness of eyelid or inner lining of eye (eye drops and eye ointment only)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Contamination: To avoid possible contamination of the drops or ointment, do not touch the dropper tip or the ointment tube tip to any surface.

Organism overgrowth: Use of this medication occasionally allows overgrowth of microorganisms, such as fungi that are not killed by the antibiotic. If this occurs, or if irritation or sensitization to any of the components of this preparation develops, contact your the doctor.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if this medication passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of this medication for children under the age of 6 years have not been established.

If you are applying additional medications to the area being treated, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.