Indications
- Injection (in hospital): serious bacterial infections such as blood infection (sepsis), infections in newborn babies, complicated urinary tract infections, pneumonia, abdominal infections, and heart valve infection (endocarditis) together with other antibiotics
- Eye drops or ointment: bacterial eye infections such as conjunctivitis
- Ear drops: bacterial infection of the outer ear canal
- Cream or ointment: minor bacterial skin infections
How It Works
Gentamicin is an aminoglycoside antibiotic. It attaches to the part of the bacterial cell that makes proteins (the ribosome) and stops it working properly, which kills the bacteria.
Dosage and Administration
- Injection: given by a doctor or nurse into a vein or muscle. The dose depends on body weight and kidney function, is often given once a day, and blood levels are checked, as prescribed.
- Eye drops: usually 1 or 2 drops into the affected eye every 4 hours, or more often at first for severe infection, as advised.
- Ear drops: usually 2 or 3 drops into the affected ear three or four times a day, as advised.
- Cream or ointment: apply a thin layer to the affected area three or four times a day.
Use eye, ear and skin forms for the time advised, usually not more than 7 to 10 days, unless the doctor says otherwise.
Interactions
- Other medicines that can harm the kidneys or hearing, such as Furosemide, Vancomycin, Amphotericin B, Cisplatin and Ciclosporin, increase the risk of damage with the injection.
- Muscle relaxants used during anaesthesia: the injection can increase muscle weakness.
Contraindications
- Allergy to gentamicin or other aminoglycoside antibiotics such as Amikacin or Tobramycin
- Myasthenia gravis (a condition causing muscle weakness), for the injection
- Ear drops: a known or suspected hole in the eardrum
Side Effects
Injection: can affect the kidneys and the inner ear, causing hearing loss, ringing in the ears, dizziness or poor balance; rarely muscle weakness or rash. Eye and ear drops: brief stinging, itching or redness. Cream: local irritation.
Get urgent medical help if there is new hearing loss, ringing in the ears, a spinning feeling, much less urine than usual, swelling of the face, lips or throat, difficulty breathing, or a severe rash.
Pregnancy and Lactation
The injection can harm the unborn baby’s hearing and kidneys, so it is used in pregnancy only when essential. Eye, ear and skin forms are absorbed very little and can be used with medical advice. Small amounts pass into breast milk; breastfeeding can usually continue with the doctor’s advice, watching the baby for diarrhoea or thrush.
Precautions and Warnings
- With the injection, kidney function and blood levels are checked, especially in older people, newborns and people with kidney disease or dehydration.
- Tell the doctor about any hearing or balance problem.
- Do not use the eye or ear drops for longer than advised, as resistant germs or fungi may grow.
- Do not touch the dropper tip to the eye or ear.
Overdose
An injection overdose can damage the kidneys and hearing. It is treated in hospital, and dialysis can remove gentamicin from the blood. Swallowing drops or cream is unlikely to cause harm, but seek advice if a child swallows a large amount.
Therapeutic Class
Aminoglycoside antibiotic.
Storage
Store below 30°C in a dry place, away from light and out of the reach of children. Do not freeze. Throw away eye or ear drops 4 weeks after opening.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.