Get our free Garamycin coupon and be eligible to receive a discount. You can reduce your Garamycin cost by up to 75% with our free Garamycin discount card. Bring it to a participating pharmacy near you to save on your prescription medication.Gentamicin is an antibiotic. It fights bacteria in the body. Gentamicin is used to treat severe or serious bacterial infections. Gentamicin may also be used for purposes other than those listed in this medication guide.