Genticin injection (Gentamicin)

How does it work?

Genticin injection contains the active ingredient gentamicin, which is a type of medicine called an aminoglycoside antibiotic. Antibiotics are used to treat infections caused by bacteria. (NB. Gentamicin is also available without a brand name, ie as the generic medicine).

Gentamicin works by affecting the bacteria's production of certain proteins that are necessary for their survival. It causes the bacteria to produce abnormal and faulty proteins. This ultimately kills the bacteria and clears up the infection.

Gentamicin is not absorbed from the gut and is therefore only given by injection or infusion (drip). It is only used in the treatment of serious infections.

To make sure the bacteria causing an infection are susceptible to gentamicin, your doctor may take a tissue sample, for example a blood, urine or sputum sample.

What is it used for?

Gentamicin injection is used to treat serious widespread infections such as those listed below, when these are caused by susceptible bacteria.

  • Bacterial infections of the central nervous system (brain and spinal cord), for example meningitis.
  • Bacterial infections of the blood (septicaemia or blood poisoning).
  • Severe bacterial infections in newborn babies.
  • Severe bacterial chest infections, such as pneumonia.
  • Inflammation of the lining of the heart cavity and heart valves due to infection (bacterial endocarditis).
  • Bacterial infections of the kidneys (acute pyelonephritis).
  • Inflammation of the prostate gland due to bacterial infection (prostatitis).
  • Bacterial infections of the bile duct or gall bladder.


  • During treatment with this medicine you will need to have regular blood tests to monitor the level of the medicine in your blood. This is to make sure that your dose is not too high to cause side effects, or too low to be effective against the infection.
  • This type of medicine can cause side effects on the kidneys and ears, particularly if used in high doses or for prolonged periods of time. For this reason, your kidney function and hearing should be monitored during treatment.
  • You should let your doctor know if you experience any hearing loss, sensation of ringing or other noise (tinnitus) in the ears, dizziness or unsteadiness at any point during treatment.
  • Wherever possible, a course of treatment with this medicine should not exceed seven days. If treatment is needed for longer than this, additional monitoring for side effects may be needed.

Use with caution in

  • Newborn babies and infants.
  • Elderly people.
  • Decreased kidney function.
  • Obesity.
  • Conditions that cause muscle weakness, for example Parkinson's disease.

Not to be used in

  • The muscular condition myasthenia gravis.

This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.

Pregnancy and breastfeeding

Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.

  • This medicine should not be used during pregnancy unless considered essential by your doctor to treat a life-threatening infection. If used during pregnancy it is essential that the level of medicine in the mother's blood is closely monitored. Seek further medical advice from your doctor.
  • This medicine passes into breast milk in small amounts. However, a nursing infant is unlikely to absorb harmful amounts of the medicine from the milk, unless they have an inflammatory bowel disease. Seek further medical advice from your doctor.

Side effects

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here does not mean that all people using this medicine will experience that or any side effect.

  • Nausea and vomiting.
  • Rash.
  • Sore mouth.
  • Damage to hearing.
  • Damage to vestibular function within the ear. Symptoms include giddiness or dizziness, spinning sensation, unsteadiness, or loss of balance.
  • Damage to kidney function.
  • Problems with liver function.
  • Disturbances in the normal numbers of blood cells in the blood.
  • Inflammation of the large intestine (colitis).
  • Decreased level of magnesium in the blood (hypomagnesaemia).

The side effects listed above may not include all of the side effects reported by the medicine's manufacturer.For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.

How can this medicine affect other medicines?

It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while being treated with this one, to ensure that the combination is safe.

There may be an increased risk of side effects on the kidneys if this medicine is used in combination with other medicines that can affect kidney function, such as the following:

  • amphotericin
  • capreomycin
  • cephalosporin antibiotics, eg cephaloridine
  • ciclosporin
  • cisplatin
  • colistin
  • polymixin
  • tacrolimus
  • teicoplanin
  • vancomycin.

The combination of gentamicin with these medicines should be avoided wherever possible. If your doctor thinks both medicines are essential then your kidney function should be closely monitored.

There may be an increased risk of side effects on the ear (such as hearing or balance problems) if this medicine is used in combination with the following medicines:

  • capreomycin
  • cisplatin
  • loop diuretics such as furosemide and etacrynic acid (the combination of gentamicin with a loop diuretic should be avoided)
  • teicoplanin
  • vancomycin.

Gentamicin may oppose the effects of neostigmine and pyridostigmine used to treat the muscular condition myasthenia gravis.

Gentamicin may increase the blood level of a medicine used to treat heart failure called digoxin.

There may be an increased risk of side effects if this medicine is used in combination with botulinum toxin.

There may be an increased chance of the level of calcium in the blood dropping too low (hypocalcaemia) if this medicine is used in combination with bisphosphonates, eg alendronate.

In newborn babies, indometacin may increase the amount of gentamicin in the blood.

Other medicines containing the same active ingredient

Cidomycin injection Genticin eye/ear drops

Gentamicin injection is also available without a brand name, ie as the generic medicine.