Medicines & Supplements A to Z > Gentamicin


Last updated on 02/07/2021.

Overview   |   Dosage   |    Side Effects   |   Precautions  |   Tips  |   Where To Buy  

GENERIC NAME: Gentamicin


BRAND NAME(S) IN HONG KONG: Garamycin 甲黴素, Quadriderm 可立淨, Triditol-G 利膚適

DRUG CLASS: Antibiotics

SUB CLASS: Aminoglycosides

USED FOR: Bacterial skin infections, bacterial eye infections, outer ear infections

– 0.1%, 0.3% (cream)
– 0.94% (ointment)
– 0.3% (eye/ear drops)
– 0.3% (eye ointment)
– 40 mg/ml, 80 mg/2ml, 280 mg/2ml (injections)

What is Gentamicin for?

Gentamicin belongs to a class of medications called aminoglycoside antibiotics. It works by inhibiting the growth of bacteria and is used to treat a wide variety of bacterial infections. It does not work for virus or fungus infections. Topical Gentamicin may be used for skin and eye infections. It can also be given by injections to treat systemic and severe bacterial infections.

Gentamicin is often used in combination with corticosteroids, such as Betamethasone, to treat skin infections.

How to use it?

Gentamicin is available in many different products that can be used on the skin, in the eye, or in the outer ear. Wash your hands before and after applying this medication.

The following dosage applies to both children and adults. Your doctor will advise you on the frequency of application depending on your infection.

Bacterial eye infections
Eye drops: Frequency of eye drops depends on the severity of the infection. For severe infections, apply 1 drop at least every 2 hours; for less severe infections, 3-4 times daily is generally sufficient. Frequency should be reduced as infection is controlled and continues for 48 hours after healing.

Otitis externa (outer ear infections)
Ear drops: Apply 2-3 drops 4-5 times daily, including a dose at bedtime.

Bacterial skin infections
Cream or ointment: Apply gently to cleansed affected areas 3-4 times daily.

What are the side effects of Gentamicin?

Common side effects of Gentamicin include tinnitus (if applied in the ear). skin irritation or allergic contact dermatitis (if applied topically).

Who should not take Gentamicin?

– People allergic to Gentamicin or any component of the formulation.
– People who are allergic to aminoglycosides.
– Patients with myasthenia gravis.
– Patients with a perforated tympanic membrane.

Pharmacist Tips:

– You must complete the entire course of this antibiotic, or else, the infection will not be properly controlled.
– Since Gentamicin is indicated for infection, remember to clean your hands before applying the cream or using eye/ear products.
– Applying the medication to the eye may cause blurred vision. If affected, do not drive or operate machinery.

Common dosing schedule:
Your doctor will advise you on the frequency of application depending on your infection.

Some common medications Gentamicin may interact with:
– Non-steroidal anti-inflammatory drugs, e.g. Ibuprofen, Ketorolac, Mefenamic Acid

Please notify your doctor or pharmacist if you are taking the above medication, dosage adjustments might be needed.

Where to buy Gentamicin in Hong Kong?

In Hong Kong, Gentamicin is a prescription only medicine, and requires a prescription from a doctor to be purchased in a pharmacy. It can also be obtained from doctors. To find a pharmacy near you, refer to the list of pharmacies (“Authorized Sellers of Poisons”) from the Hong Kong Department of Health. 

For more information about drug names and ingredients, you can visit Hong Kong’s Drug Office at

Need more information?

For detailed information about the use of Gentamicin in children, pregnancy and breastfeeding, and for questions about drug interactions, please check with your pharmacist or doctor.

Disclaimer: our goal is to provide you with the most relevant drug information and common dosage for Hong Kong. This information does not constitute medical advice. For specific treatment recommendations and advice, always discuss with your doctor or pharmacist, and follow the instructions included with your specific medicine.