SN instructed patient/ caregiver about Gentamicin. SN explained that Gentamicin is an antibiotic that fights bacteria. Gentamicin is used to treat severe or serious bacterial infections. You should not use this medicine if you are allergic to gentamicin or similar antibiotics such as amikacin, kanamycin, neomycin, paromomycin, streptomycin, or tobramycin. Common side effects may include: vision problems; nausea, vomiting, loss of appetite, weight loss; a light-headed feeling, like you might pass out; itching or rash; pain where the medicine was injected; a headache, mood changes; or joint pain. Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.