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Gentamicin Side Effects

Medically reviewed by Last updated on Aug 1, 2023.

Applies to gentamicin: injection solution.


Injection route (Solution)

Therapy has been associated with potential neurotoxicity, ototoxicity, and nephrotoxicity. Patients with impaired renal function, advanced age, dehydration, and those who receive high doses or prolonged therapy are at an increased risk of toxicity. Monitor renal and auditory function during therapy and discontinue therapy or adjust dose if there is evidence of ototoxicity or nephrotoxicity. Aminoglycoside-induced ototoxicity is usually irreversible. Serum concentrations of aminoglycosides should be monitored when feasible to assure adequate levels and to avoid potentially toxic levels. Concurrent use of other potentially neurotoxic or nephrotoxic agents, or potent diuretics should be avoided. Aminoglycosides can cause fetal harm when administered to a pregnant woman.

Serious side effects of Gentamicin

Along with its needed effects, gentamicin may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor or nurse immediately if any of the following side effects occur while taking gentamicin:

Incidence not known

Other side effects of Gentamicin

Some side effects of gentamicin may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Incidence not known

For Healthcare Professionals

Applies to gentamicin: compounding powder, injectable solution, intravenous solution.


The most frequently reported adverse effects associated with treatment are ototoxicity and nephrotoxicity. These forms of toxicity occur more frequently in patients who experience prolonged exposure to serum trough concentrations of greater than 2 mcg/mL. Patients with renal insufficiency are at an increased risk of developing toxicity.[Ref]

Nervous system

Common (1% to 10%): Myasthenia gravis aggravated/unmasked, neuromuscular blockade

Very rare (less than 0.01%): Convulsion, encephalopathy, lethargy, peripheral paresthesia, polyneuropathy, vestibulocochlear nerve damage with potential involvement of the organ of balance/hearing

Frequency not reported: Central neurotoxicity, generalized burning, headache, lethargy, myasthenia gravis-like syndrome, numbness, peripheral neuropathy, pseudotumor cerebri, skin tingling, toxic neuropathy, vestibular damage[Ref]

Vestibular damage occurred more commonly when peak levels of 10 mcg/mL or trough levels of 2 mcg/mL were exceeded.[Ref]


Uncommon (0.1% to 1%): Nausea, stomatitis, vomiting

Rare (0.01% to 0.1%): Pseudomembranous colitis

Frequency not reported: Increased salivation[Ref]


Uncommon (0.1% to 1%): AST increased, ALT increased, blood bilirubin increased

Very rare (less than 0.01%): Alkaline phosphatase increased

Frequency not reported: Transient hepatomegaly[Ref]


Uncommon (0.1% to 1%): Blood dyscrasias

Very rare (less than 0.01%): Thrombocytopenia

Frequency not reported: Anemia, decreased reticulocyte counts, eosinophilia, granulocytopenia, increased reticulocyte counts, leukopenia, splenomegaly, transient agranulocytosis[Ref]


Rare (0.01% to 0.1%): Electrolyte disturbances, hypocalcemia, hypokalemia, hypomagnesemia

Frequency not reported: Decreased appetite, decreased serum calcium, decreased serum magnesium, decreased serum potassium, decreased serum sodium, hypovolemia, tetany, weight loss[Ref]


Very rare (less than 0.01%): Elevated serum creatinine, elevated serum urea, kidney damage, oliguria, reduction of glomerular filtration rate

Frequency not reported: Acute renal failure, blood urea nitrogen (BUN) increased, increased nonprotein nitrogen (NPN), nephrotoxicity[Ref]

Nephrotoxicity, demonstrated by the presence of casts, cells, protein in the urine, rising BUN, NPN, serum creatinine, and/or oliguria, was usually reversible with treatment withdrawal, and was more common in patients with preexisting renal dysfunction, those receiving concomitant treatment with other nephrotoxic agents, and trough serum concentrations above 2 mcg/mL.

Signs of kidney damage included cylindruria, hematuria, oliguria, proteinuria, and elevated serum creatinine and urea.[Ref]


Frequency not reported: Cells in urine, cylindruria, hematuria, proteinuria, urinary casts[Ref]


Very rare (less than 0.01%): Confusional state, depression/mental depression, hallucination

Frequency not reported: Acute organic brain syndrome, confusion[Ref]


Very rare (less than 0.01%): Ototoxicity, tinnitus

Frequency not reported: Diminishing high-tone acuity, extravasation, febrile response, fever, hearing loss, roaring in the ears[Ref]


Very rare (less than 0.01%): Pruritus, urticaria

Frequency not reported: Alopecia, itching, purpura, rash[Ref]


Very rare (less than 0.01%): Anaphylactic reaction

Frequency not reported: Anaphylactoid reaction, hypersensitivity[Ref]


Frequency not reported: Fat necrosis, injection site infection, injection site pain, local irritation, subcutaneous atrophy[Ref]


Frequency not reported: Hypertension, hypotension, phlebitis, venous thrombosis[Ref]


Frequency not reported: Laryngeal edema, postoperative respiratory distress, pulmonary fibrosis, respiratory depression[Ref]


Frequency not reported: Joint pain, muscle twitching, muscle weakness[Ref]


Frequency not reported: Visual disturbances[Ref]


Frequency not reported: Increased serum lactate dehydrogenase (LDH)[Ref]


1. Product Information. Garamycin (gentamicin). Schering-Plough Corporation. 2007;PROD.

2. Cerner Multum, Inc. UK Summary of Product Characteristics.

3. Cerner Multum, Inc. Australian Product Information.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.