Gentamicin (Injection)

Gentamicin injection is the usual drug of choice for certain serious infections that are caused by the presence of certain bacteria in different locations in the body.


The antibiotic drug Gentamicin is known in the US as Garamycin. It is an injectable medicine that is only administered in a hospital or clinic setting, either by or under the supervision of a suitably trained medical professional.

Gentamicin is one of a group of antibiotic drugs called aminoglycosides. The medicine works by stopping the proliferation and spread of the bacterium. It should be noted that this medication is not a broad-spectrum antibiotic and it is not effective in treating flu, colds, or other viral infections. Gentamicin is usually used to treat serious bacterial infections when other drugs have failed to be effective.

Gentamicin can cause serious side effects, including causing damage to your hearing and to your kidneys. These unwanted effects are more likely to affect newborns and geriatric patients, and you should discuss this if it applies in your case.

Conditions treated

  • Certain bacterial infections

Type of medicine

  • Aminoglycoside antibiotic

Side effects

In addition to the effects it is designed to have, some medicines can cause a few unwanted side effects. Not everyone who is treated with gentamicin will notice anything untoward, but if you do, you may require further medical intervention.

If you notice any of the side effects that are mentioned in the following list, you must check with your treating physician or nurse right away:

  • Wheezing
  • Weight loss
  • Chest discomfort
  • Unusual feelings of tiredness or weakness
  • Unusual bleeding or bruising
  • Trembling
  • Tightness of the chest
  • Swollen glands
  • Swelling of the lower limbs or feet
  • Sweating
  • A stiff neck
  • Ulcers, white spots, or sores affecting the lips or inside of the mouth
  • Sore throat
  • Slow or irregular breathing
  • Slow or fast heartbeat
  • Skin rashes
  • Sensation of spinning
  • Convulsions
  • Pain and fullness of the right upper abdomen or stomach
  • Swelling and puffiness of the eyes, eyelids, face, lips, or tongue
  • Red pinpoint spots on the skin
  • Pale skin
  • Blue or pale lips, fingernails, or skin
  • Tingling or numbness around the mouth, feet, or fingertips
  • Nervousness
  • Nausea or vomiting
  • Muscle spasms or twitching
  • Muscle pain or weakness
  • Cramps in the hands, arms, feet, legs, or face
  • Mental or mood changes
  • Poor appetite
  • Joint pains
  • Itching
  • Irritability
  • Irregular, fast, slow, or shallow breathing
  • Irregular heartbeat
  • Increased thirst
  • Hoarseness
  • Hives
  • Hearing loss
  • Headache
  • Hallucinations
  • Fever with or without chills
  • Rapid heartbeat
  • Eye pain
  • Dry mouth
  • Drowsiness
  • Feelings of faintness, dizziness, or lightheadedness when rising suddenly from a lying or seated position
  • Difficulty swallowing
  • Difficult or troubled breathing
  • Cough
  • Tinnitus
  • Confusion
  • Coma
  • Chills
  • Chest pains
  • Change in amount and frequency of urination
  • Numbness, burning, tingling, or painful sensations
  • Blurred or double vision
  • Blood in the urine
  • Tarry, black stools
  • Back pain
  • Agitation
  • Abdominal or stomach pain or cramps

There are some side effects that are sometimes caused by gentamicin that will resolve by themselves without needing any medical help. Your doctor may also be able to suggest ways of preventing or reducing the effects. However, if any of the effects mentioned here do not go away after a week or so, or if they are especially troublesome, you should tell your doctor.

  • Unusual feelings of dullness, drowsiness, weakness, tiredness, or sluggishness
  • Tunnel vision
  • Inflammation or swelling of the mouth
  • Redness of the skin
  • Purple spotting on the skin
  • Pain around the injection site
  • Over-bright appearance of lights
  • Night blindness
  • Increased salivation
  • Welts or hives
  • Seeing halos around lights
  • Hair loss or thinning of the hair
  • Disturbed color perception
  • Depression
  • Decreased appetite
  • Blurred or loss of vision

This list is not necessarily complete. Some patients do experience other effects that are not listed in this guide. If you notice any strange or unexpected effects, check with your GP or hospital doctor.


You will only be given this medication by your doctor or by your nurse. Gentamicin is administered via an injection into a vein or into a muscle.

In order for the infection to clear up completely, you will need to continue receiving this drug until the end of the course, even if you feel better after just a day or so. Gentamicin works better when there is a steady amount of the drug in your bloodstream. In order to maintain this level, you must receive doses of the drug regularly.

In order for your kidneys to keep working properly and to avoid potential kidney problems, you should drink plenty of fluids while you are receiving gentamicin.

If you do not think that you are feeling any better within a few hours of receiving your first dose of gentamicin injection, or if you consider that you are actually starting to feel worse, you must tell your nurse or treating physician straight away.


Drug interactions

There are some medications that should never be used at the same time because an interaction could occur between them. If this applies in your case, your doctor may decide to change the dose of one of your other drugs or suggest precautions that you should take to mitigate the interaction. You must tell your treating physician if you are taking any other medicines before you begin your course of treatment with gentamicin.

It is not usually recommended to use this medicine with any of the drugs listed below. Your doctor may decide not to treat you with gentamicin or may change some of your other medications:

  • Vecuronium
  • Vancomycin
  • Tubocurarine
  • Succinylcholine
  • Rocuronium
  • Rapacuronium
  • Pipecuronium
  • Pancuronium
  • Mivacurium
  • Metocurine
  • Lysine
  • Hexafluorenium
  • Gallamine
  • Furosemide
  • Foscarnet
  • Fazadinium
  • Ethacrynic Acid
  • Doxacurium
  • Digoxin
  • Decamethonium
  • Colistimethate Sodium
  • Cisatracurium
  • Cidofovir
  • Cholera Vaccine, Live
  • Atracurium
  • Ataluren
  • Alcuronium
  • Agalsidase Alfa

Patients should note that using gentamicin with any of the following medications can present an increased risk of certain side effects, although using both the medicines might be the most appropriate treatment for you. If both of the drugs are prescribed, your treating physician may elect to change the dose or frequency of one or both of them:

  • Polygeline
  • Methoxyflurane
  • Indomethacin

Other interactions

Some drugs must not be taken with food or with certain food groups, as an interaction could occur. In addition, smoking tobacco or drinking alcohol with some medications can trigger an interaction. Talk about this aspect of your treatment with your doctor before you begin receiving gentamicin.

Medical interactions

Some medical conditions can affect how gentamicin works. You must discuss your medical history fully with your doctor before your course of this drug begins.

Gentamicin contains sodium metabisulfite. This substance can cause an allergic reaction in patients who have sulfite allergy or asthma.

The following conditions must be corrected before it is considered safe to use gentamicin. If patients with these health problems receive this drug, serious side effects may occur:

  • Hypomagnesemia (low magnesium in the blood)
  • Hypokalemia (low potassium in the blood)
  • Hypocalcemia (low calcium in the blood)

Gentamicin should be used with caution in patients who have kidney disease. The effects of the drug may be increased because of its slower removal from the body.

Care should be taken when using gentamicin to treat patients who have the following conditions, as this drug can make these conditions worse:

  • Severe kidney disease
  • Nerve problems
  • Myasthenia gravis (severe muscle weakness)
  • Muscle problems


When considering whether to use a medicine, you should weigh the benefits against the risks of doing so. A discussion with your treating physician is essential before you make this decision.

Throughout the course of your treatment with gentamicin, you should attend regular update appointments with your treating physician. These check-ups will allow your GP to make sure that the drug is working properly and will also be your opportunity to mention any side effects that you may be experiencing.

You must tell your treating physician if you have ever had an odd reaction to gentamicin or to any other drugs, including over the counter products, vitamins, and herbal remedies. Be sure to mention allergies that you are aware of to particular food groups, food colors, food preservatives, or animal derivatives.

Gentamicin has not been shown to be harmful to children and is considered safe to use. However, the drug should be used with extreme caution in newborn and premature babies.

There is no research available to show that gentamicin presents a specific danger to elderly patients. However, geriatrics tend to be more prone to kidney problems, meaning that an adjustment in the dose of this medication may be appropriate.

Studies have shown that using gentamicin can present a risk to the fetus. Pregnant women must tell their treating physician that they are pregnant or if they think they have become pregnant during their course of treatment with this drug. You should take steps to avoid conception while you are taking gentamicin.

You should use an effective form of barrier contraception if your partner is receiving this drug as there is a risk that small quantities of gentamicin could be absorbed from sperm through the vaginal wall.

There is little evidence to show that gentamicin is absorbed into breast milk. However, you may wish to discontinue breastfeeding while you are receiving this drug, in case your nursing infant suffers side effects caused by ingesting some of the drug. Ask your midwife or GP for advice on finding an alternative feeding solution for your child.

While you are receiving gentamicin injections, you will need to be monitored closely by your treating physician. In addition, you or your child may need to have hearing, urine, blood, and nerve tests to make sure that the drug is not having any potentially harmful effects. It is very important that you do not miss any of these appointments.

Some patients may suffer an allergic reaction, including anaphylaxis, while using this drug. If you experience any of the symptoms listed below right after receiving your gentamicin injection, you must check with your doctor right away:

  • Hoarseness
  • Hives
  • Shortness of breath or breathing problems
  • Problems with swallowing
  • Swelling of the face, mouth, or hands
  • Itching

You should stop receiving gentamicin injection right away if you notice any sudden changes in your hearing or a loss of hearing altogether. This deafness can be accompanied by feelings of dizziness and lightheadedness. You may also feel that your surroundings are spinning. These signs can indicate that the drug has caused damage to your sense of balance or to your hearing.

In some patients, using gentamicin can cause a serious kidney problem such as Fanconi-like syndrome. If you notice any of the following signs, you must speak to your doctor right away:

  • Changes in the volume or frequency of urine
  • Breathing difficulties
  • Feeling drowsy
  • Increase in thirst
  • Poor appetite
  • Nausea or vomiting
  • Swelling of the lower legs or feet
  • Feelings of weakness

In some patients who are vulnerable to this effect, gentamicin can cause neurological problems. You must speak with your treating physician right away if you notice any feelings of skin tingling, seizures, or muscle twitches that do not disappear after a few hours.

It should be noted that using this medication prior to undergoing a surgical procedure or other procedures that mean the use of anesthetics or neuromuscular blocking agents can cause breathing difficulties, drowsiness, feeling strangely weak or tired, and being unable to breathe properly without artificial assistance. Be sure to tell your doctor or nurse that are receiving treatment with gentamicin before any such procedures.

You must not take any other medications while you are being treated with gentamicin unless you have discussed their use with your doctor. This includes not only prescription drugs, but also over the counter medications, vitamin and mineral supplements, herbal remedies, and diet pills.


Gentamicin is not generally for home use. The medicine will be given to you while you are in a medical clinic or hospital. You will therefore not be required to store this drug at your home.

Gentamicin will be kept in an appropriate storage facility and at the correct temperature in the medical facility where you are being treated.


Gentamicin is an aminoglycoside antibiotic drug that is used in the treatment of certain serious bacterial infections, usually following surgery or in a hospital setting. The drug is administered via injection by a trained medical professional. This antibiotic is not suitable for use in the treatment of common colds, coughs, viral or other more general infections. It is the drug of choice as a second line of treatment where the use of other antibiotics have failed to bring about a satisfactory result.

Gentamicin is not suitable for use with a number of existing medical conditions, because of the side effects that it causes. This is particularly applicable to the geriatric patient group and to premature or newborn babies. This drug also interacts adversely with a wide range of other prescription medications. For this reason, you must discuss your current medication therapy and your recent medical history fully with your treating physician.

Pregnant women should not receive treatment with gentamicin as the drug can be harmful to the unborn baby. Tell your treating physician if you are pregnant or breastfeeding before you agree to receive treatment with this medicine.